Answer: The answer that indicates the primary accent in the word "cavil" in the dictionary is the second one: cav´ il.
Step-by-step explanation: The word "cavil" is made up of two syllables: "cav" and "il"; however, the primary accent falls on the first syllable ("cav"). In that way, "cav" is the syllable that has to be emphasized, that is to say it has to be pronounced louder and longer than "il". In dictionaries, the strongest emphasis in a word is signaled by means of a "´". In that way, the second answer (cav´ il) is the one that divides the word "cavil" into syllables accurately and the one that indicates its correct primary accent.