As we all know, “true” and “false” are direct antonyms. “Fake” is an adjective that means not genuine, so we’re looking for the word that has the closest meaning to “genuine.” “Authentic” is an adjective that means genuine and true, not fake.

Of the answer choices, “authentic” is the best choice.

“Intangible” is an adjective that means not able to be touched or sensed. Since “physical” is an adjective that means perceived through the senses, the words are antonyms. We’re looking for a pair of words that are antonyms, and that have the closest meaning to “physical” and “intangible.”

“Real” is an adjective that means actually existing, not imagined or supposed. “Fake” is an adjective that means not genuine. Neither word relates specifically to the senses. We can rule out this choice.

 “Simple” and “complex” aren't specifically related to the senses either, so we can rule out this choice.

“Substantial” is an adjective that can mean either real and tangible or of considerable importance, size, or worth. Since the second word in this pair is “unimportant,” we can rule out this choice.

 “Concrete” is an adjective that means existing in material or physical form. “Abstract” is an adjective that means not having a physical existence.

 Of the answer choices, “CONCRETE is to ABSTRACT” is the best choice.

"Emaciated" and "obese" are both physical descriptions, and they are opposites. "Emaciated" means unhealthily thin, while "obese" means unhealthily fat. "Tall" and "short" are both physical descriptions, and they are opposites.

None of the other analogies have a similar relationship:

Clever and absent-minded are both personality descriptions, but they are not directly opposed in meaning. Dirty and messy are both states of cleanliness, and they are not opposites. Water is not a physical description, although dry is; water and dry are not opposites, wet and dry are opposites. Towering is a physical description, but dwarf is a noun that means a mythical creature who is short.  

"Agitated" and "calm" are both mental states of being, and they are opposites. "Joyful" and "miserable" are both mental states of being, and they are opposites as well.

None of the other analogies have this relationship:

Anger and Passion are both mental states of being, but they are not opposites.

Similarly, joyful and scared are both mental states of being, but they are not opposites.

Lake and ocean are not mental states of being.

Empty and full are opposites, but are not mental states of being.

"Scrupulous" and "careless" are antonyms. "Scrupulous" means careful, diligent and attentive to details. "Careless" means not giving sufficient attention to a task. Similarly, naive and wise are antonyms. "Naive" means lacking experience or wisdom, while "wise" means having experience, knowledge and good judgment. 

None of the other responses are antonyms of each other:

"Untenable" means a position that is unable to be defended or supported. "Flimsy" means something light, insubstantial and easily damaged.

"Devious" and "deceitful" are synonyms, and both mean untrustworthy.

"Destitute" and "impoverished" are both synonyms. "Impoverished" means exhausted of strength, vitality or wealth, and "destitute" means lacking a basic, minimal amount of money.

"Wizened" and "old" are synonyms. "Wizened" means wrinkled with age or shriveled, while "old" means advanced in age or no longer young.

When you lend an object, you give it to someone temporarily, when you borrow an object, you take it temporarily. Thus, borrow and lend are antonyms. Similarly, brighten means to make brighter, while fade means to make less bright.

None of the other analogies have this relationship.

Steal means to illegally take an object, while make means to create something.

Donate means to provide something desirable free of charge, while manipulate means to either physically use one's hands on an object, or to influence a person or situation.

Beg means to ask for money or food, while steal means to illegally take something.

Clumsy means ungainly, or moving in an awkward uncontrolled manner, while crippled means unable to walk or unable to move, due to an ailment.

Opulent and impoverished are antonyms. Opulent means excessively wealthy and luxurious or flashy, while impoverished means very poor. Similarly, sick is the opposite of healthy.

None of the other analogies have this relationship:

Black and blue are both colors, and they are not opposites.

Tidy means neat, but tidy is not the opposite of broken. Broken means not whole, or damaged.

Bent and curved are synonyms, and mean not perfectly linear, such as the shape of a circle or an oval.

Naive means not wise, or not worldly, and gullible means easily tricked. People who are naive are often gullible. The two words are not opposites.

Dirty and clean are considered to be opposites, so we must find the opposite of pure. Pure means devoid of contaminations, so the opposite of pure is "contaminated."

None of the other words are the opposite of pure.

Avian means related to birds. 

Complex means not simple.

Messy means not neat, which is related to the concept of impurity, but not exactly the opposite of pure.

Cure is a word that means to resolve a sickness. While it rhymes with pure, it is not the opposite.

"Grievous" means of great importance, serious and significant. As such it is an antonym of "trivial," which means not important, of lesser significance, irrelevant. So, to solve this analogy you need to figure out which of these words is opposite in meaning to "dull." "Dull" means lacking color, energy, or excitement, boring and uninteresting. The best available antonym is therefore "vibrant" which means colorful, energetic. Additionally, "pious" means devout, deeply religious; "enterprising" means hardworking and innovative, working hard to come up with new solutions; "porous" means filled with holes; "whimsical" means quirky, silly.

"Benign" means not dangerous, harmless, not likely to cause harm. It is therefore an antonym of "dangerous." So, to solve this analogy you need to determine which of these is an antonym of "culpable." Well, "culpable" means guilty, responsible for an offense, not innocent. So, the best possible antonym is "innocent." Additionally, "intrepid" means bold and adventurous; "insane" means crazy, not sane; "invalid" means not valid, not legitimate, not correct; "impulsive" means prone to making decisions without thinking about it.