If someone makes an assertion, it means that they make a declaration or declare something in particular.

"Ascertain" is a verb that means "find something out for certain; make sure of." So, "forget" cannot be the correct answer, because it means the opposite of "ascertain." "Deduce," however, is a verb that means "arrive at a fact or a conclusion by reasoning; draw as a logical conclusion," and because it is the answer choice closest in meaning to "ascertain," it is the correct answer.

"Acknowledge" is a verb that can mean "accept or admit the existence or truth of," "recognize the fact or importance or quality of," or "show that one has noticed or recognized (someone) by making a gesture or greeting." So, we need to pick out an answer choice that means something like "accept," "recognize the importance of," or "show that one has noticed or recognized someone." "Deny," then, cannot be the correct answer because "deny" means " state that one refuses to admit the truth or existence of," making it an antonym of the first meaning of "acknowledge," not a synonym. "Admit," however, is a verb that can mean "confess to be true or to be the case, typically with reluctance," and because "admit" is the answer choice closest in meaning to "acknowledge," "admit" is the correct answer.

"Consider" is a verb that can mean "think carefully about (something), typically before making a decision," "regard (someone or something) as having a specified quality," or "believe; think." So, we need to pick out an answer choice that means something like "think carefully about," "regard," or "believe." So, "ignore" cannot be the correct answer because "ignore" is an antonym, not a synonym, of "think carefully about." "Deem," however, is a verb that means "regard or consider in a specified way," and because "deem" is the answer choice closest in meaning to "consider," "deem" is the correct answer.

"Enlighten" is a verb that can mean "give (someone) greater knowledge and understanding about a subject or situation" or "give (someone) spiritual knowledge or insight." So, we need to pick out an answer choice that means something like "give someone greater knowledge" or "give someone spiritual knowledge." "Mistake" cannot be the correct answer, then, because "mistake," when used as a verb, means "be wrong about," not "give someone greater knowledge." "Inform," however, is a verb that means "give (someone) facts or information; tell," and because "inform" is the answer choice closest in meaning to "enlighten," "inform" is the correct answer.

“Interrogate” is a verb that means “ask questions of someone aggressively or formally,” so we need to pick out an answer choice that means something like “ask questions of someone aggressively.” That means that “reply” cannot be the correct answer, because “reply” means “say something in response to something someone has said” when used as a verb, making it an antonym, not a synonym, of “interrogate.” “Question,” however, is a word that can mean “ask questions, especially in an official context” when used as a verb, and because “question” is the answer choice closest in meaning to “interrogate,” “question” is the correct answer.

“Persuade” is a verb that can mean “to convince someone,” so we need to pick out an answer choice that means something like “reason with someone to change their beahvior.” That means that “discourage” cannot be the correct answer, because “discourage” can mean “cause to lose confidence,” making it an antonym, not a synonym, of “persuade.” “Coax,” however, is a verb that means “to persuade someone gently,” and because “coax” is the answer choice closest in meaning to “persuade,” “coax” is the correct answer.

“Bicker” is a verb that means “ argue trivial things,” so we need to pick out an answer choice that means something like “argue.” That means that “concur” cannot be the correct answer, because “concur” can mean “agree,” making it an antonym, not a synonym, of “bicker.” “Squabble,” however, when used as a verb, means “quarrel over trivial things,” and because “squabble” is the answer choice closest in meaning to “bicker,” “squabble” is the correct answer.

The word "contend" means to challenge or to compete. "Challenge" is the best choice as it is a part of the definition of "contend" and is often used as a synonym for it.

The word "perplex" means to confuse. "Perplex" is the best choice because it is a synonym of "confuse." Considering the other choices, "combine" means to put together, "ambiguous" means uncertain or having many meanings, and "fickle" means frequently changing or inconstant.