Select the true statement in this group.
select one:
a. a noun phrase consists of a headword noun along with all of the words and phrases that modify—or describe-- the noun.
b. in an interrogative sentence, the subject is understood.
c. an expanded verb consists of auxiliary verbs, the predicate headword, and all modifiers of the verb.
d. forms of have, has, had can serve as auxiliary verbs but not as main verbs.