Someone who is "corpulent" is overweight or fat, so "fat" is the correct answer. For clarification, "delirious" means insane or feverish, "quirky" means unusual and silly, and "nomadic" means wandering or itinerant.

"Frail" means weak and feeble.

Audible means loud enough to be heard. An example would be, "The sound was audible even over the loud music of the marching band."

"Auditory" deals with things that are "audible," but these are not synonyms. A "faint sound" might be "barely audible," but again this is not a synonym, since loud sounds can be "clearly audible."

“Robust” is an adjective that means full of strength and health. While “aggressive” and “energetic” might be characteristics of a “robust” person, they aren’t close synonyms. Of the answer choices, “healthy” has the closest meaning.

"Turgid" means "swollen" or congested. 

"Dissolved" means to be broken down into a liquid form.

"Shrunken" means became smaller.

"Succulent" means tender or juicy.

"Emaciated" means abnormally thin or weak.

"Potent" means "powerful" or having a big influence or effect. 

None of the other words are synonymous. Things that are "alcoholic" can certainly be potent, but "alcoholic" simply means containing alcohol. "Calming" means to make someone or something tranquil. "Poisonous" means capable of causing illness or death if taken into the body. To be "morbid" means to take an abnormal degree of interest in death and disease.

"Sweltering" is an adjective that typically refers to weather and means "uncomfortably hot."

"Windy" means breezy or the weather pattern of significant flow. "Stringent," typically referring to rules or requirements, means strict or firm. "Frigid" means very cold. "Boiling" means bringing liquid to the temperature at which it changes from liquid to gas and evaporates.

"Oblong" is an adjective that means having a long shape, for example an oval is an oblong shape.

"Rigid" means inflexible or resistant to change. "Flat" means smooth, or a surface that doesn't change its elevation. When describing a human, "flat" means dull or without emotion. "Curved", when referring to a line, means not perfectly straight. "Stout" means stocky or solidly built.

"Decrepit" and "dilapidated" both mean old, worn out, or falling apart due to neglect. Someone who is skeptical has doubts or is unconvinced, and someone who is suspicious also has doubts or distrust. "Pessimistic," the opposite of optimistic, means having a negative outlook on life, and "scandalous" means disgraceful or outrageous.

"Nondescript" describes something that lacks distinct or interesting characteristics, something that is not remarkable in any way. Something silent makes no noise, something functional works or functions correctly, and something unusual is strange or out of the ordinary. "Magnificent" is a word meaning beautiful, excellent, or striking.