"Nullify" means to make something invalid or to cancel something, so the correct answer is “invalidate.” For clarification, "supplant" means replace.

"Reasonable" means logical, rational, or possessing reason.

To illuminate something means to shed light on it, to make it clear. The part of the word -lum- generally refers to light or clarity as in illuminate, luminous, illumination, etc.

"Antagonize" means alienate or provoke, so "provoke" is the correct answer. "Undermine" means weaken. "Ajar" is an adjective that means slightly open. "Barter" is a verb that means trade or negotiate the price of an item. "Retreat" means withdraw or move back to a previous location.

If you “vilify” someone, you say or write harsh and critical things about them. It is related to the root word "villain." Remember that the suffix "-ify" means to make or invest with attributes. "Villify" is similar in meaning to "abuse," which means to treat harshly or unfairly. To clarify the other terms, “declare” means say publically; “enlarge” means get bigger.

The suffix "-able" means able to be,so “fathomable” means able to be fathomed—that is, able to be understood. Notice how all of the answer choices use "-able" or ­"-ible"; this means that you will have to try and figure out which answer choice's stem is most similar to “fathom.” The correct answer is "comprehensible" because "comprehend" means understand. As for the other answer choices, “amiable” means friendly or sociable; “agreeable” means pleasant or easy-going; “intangible” means not able to be touched or not able to be defined, and "comfortable" means cozy and pleasant.

"Reprehensible" means disgraceful or shameful, so "shameful" is the correct answer. None of the other answer choices are close in meaning to "shameful": “optical” means related to seeing; “auditory” means related to hearing; "triumphant" means victorious; and "bewildered" means very confused.

The prefix equ- means equal, same, so the word “equalize” means to make equal. Of the five answer choices this is most similar in meaning to “balance.” To provide further help, “demonstrate” means to show how to do something; “laud” means praise; “condemn” means criticize, say is wrong.

The suffix -cide means related to killing, and the prefix homi- means related to humans, or to sameness (depending on context). Here it could be said to mean either related to humans or related to being the same, because “homicide” involves a human killing a human, or “murder.” To provide further help, “theft” is stealing; “aggression” is hostility, anger; “passivity” is the opposite of aggression, sometimes calm or weak; “incentive” is motivation, the reason for doing something. 

The prefix gyne­- means relating to women or to women’s reproductive systems. “Gynecology” is the medicine that specializes in treating women. To provide additional help, the medicine that specializes in treating children is called “pediatrics.”