The answer is B. This includes helping verbs or modals like have, could would and adverbs like who, what, where, when, why and how.
A is not the answer, I like cake vs. What is your name? both are short and statements like this are common.
C is not the answer because we often use pronouns in questions and adjectives are used as descriptions regardless of statement or question. Where is she? What is it? Disprove the pronoun aspect. Is it a blue color? Disproves the adjective aspect.
D is not the answer because of questions of fact like, what time is it? There is no direct or indirect object because the verb is a linking verb, used for a statement, connecting or linking the subject to the fact, without an object.
