Explanation
Choice A is the best answer. The convention being tested in fragmentation, which refers to a group of words that is not a complete sentence but is punctuated as one. Relative clauses, such as the one beginning with “who,” require a verb that can function as the main verb of a clause. This choice correctly supplies the clause with the present tense verb “require.”
Choice B: The to-infinitive “to require” cannot function as the main verb of the sentence.
Choice C: The past tense verb “required” does not agree in tense with the previous verb of the sentence “holds.”
Choice D: “Having required” is a participle and cannot function as the main verb of the sentence.
✨ Expert's Tip ✨
To check whether your answer choice is correct, create a sentence using the antecedent (the word preceding the relative pronoun) as the subject and the verb from the relative clause as the main verb.
