“Warrant” is a word that can be used as a noun or a verb, but because all of the potential answer choices are verbs, we will need to consider “warrant” as a verb. When used as a verb, “warrant” can mean “justify or necessitate a certain course of action.” So, we need to pick out an answer choice that means something like “justify” or “guarantee.” That means that “deny” cannot be the correct answer, because “deny” can mean “state that one refuses to admit the truth or existence of” a meaning very distant from that of “warrant.” “Deserve,” however, is a verb that means “do something or have or show qualities worthy of reward or punishment,” and because “deserve” is the answer choice closest in meaning to “warrant,” “deserve” is the correct answer.

“Enunciate” is a verb that can mean “say or pronounce clearly,” “express something in clear or definite terms,” or “proclaim.” So, we need to pick out an answer choice that means something like “say clearly,” “express something in clear or definite terms,” or “proclaim.” That means that “murmur” cannot be the correct answer, because “murmur,” when used as a verb, means “say something in a low, soft, or indistinct voice,” making it an antonym, not a synonym, of “enunciate.” “Articulate,” however, when used as a verb, can mean “pronounce something clearly and distinctly,” and because “articulate” is the answer choice closest in meaning to “enunciate,” “articulate” is the correct answer.

“Ubiquitous” is an adjective that means “found everywhere,” so we need to pick out an answer choice that means something like “found everywhere.” That means that “limited” cannot be the correct answer, because “limited” can mean “few, small, or short,” making it an antonym, not a synonym, of “ubiquitous.” “Pervasive,” however, is an adjective that is used especially of an unwelcome influence or physical effect and means “spreading widely throughout an area,” and because “pervasive” is the answer choice closest in meaning to “ubiquitous,” “pervasive” is the correct answer.

“Captivate” is a verb that means “attract and hold the interest and attention of; charm,” so we need to pick out an answer choice that means something like “charm.” That means that “disgust” cannot be the correct answer, because “disgust,” when used as a verb, means “cause someone to feel revulsion or profound disapproval,” making it an antonym, not a synonym, of “captivate.” “Mesmerize,” however, is a verb that means “hold the attention of someone to the exclusion of all else,” and because “mesmerize” is the answer choice closest in meaning to “captivate,” “mesmerize” is the correct answer.

“Frequent” is an adjective that can mean “occurring or done on many occasions,” “doing something often; habitual,” when used of a person, or “found at short distances apart.” So, we need to pick out an answer choice that means something like “occurring in quick succession,” “habitual,” or “found at short distances apart.” That means that “occasional” cannot be the correct answer, because “occasional” means “occurring, appearing, or done infrequently and irregularly,” making it an antonym, not a synonym, of “frequent.” “Recurrent,” however, is an adjective that means “occurring often or repeatedly,” and because “recurrent” is the answer choice closest in meaning to “frequent,” “recurrent” is the correct answer.

“Beleaguer” is a verb that can mean either “lay siege to” or “beset with difficulties,” so we need to pick out an answer choice that means something like “lay siege to” or “beset with difficulties.” That means that “ease” cannot be the correct answer, because “ease,” when used as a verb, means “make less serious or severe,” making it an antonym, not a synonym, of “beleaguer.” “Trouble,” however, when used as a verb, means “cause distress or anxiety to,” and because “trouble” is the answer choice closest in meaning to “beleaguer,” “trouble” is the correct answer.

"Enigmatic" most nearly means mysterious, as in "When Harry was unexpectedly announced the winner of the race, he accepted his prize with an enigmatic smile."

"Noticeable" most nearly means distinct, evident, clear or apparent, as in "The noticeable increase in staff led to better customer service during check out."

"Valiant" most nearly means heroic or very brave, as in "The soldier charged the battle line with valiant enthusiasm."

"Nonchalant" most nearly means unconcerned, appearing casually calm and relaxed, as in "The student's nonchalant answer to the question displayed that he knew that material and was ready for the test."