Syntactic analysis is essential to understand the...

A In the sentence, "The boy" is the nominal predicate, "is reading" is the verbal predicate, and "a book" is the direct object. B In the sentence, "The boy" is the subject, "is reading" is the direct object, and "a book" is the verbal complement. C In the sentence, "The boy" is the verbal complement, "is reading" is the nominal predicate, and "a book" is the subject. D In the sentence, "The boy" is the subject, "is reading" is the verbal predicate, and "a book" is the direct object.