The “predicate” is defined as the clause in the part of a sentence with verb. This is representing about features of subject. The predicate “adjective” is that describes pronoun or noun.
In the above case, “smart” is “predicate adjective” used to describe nature of students (noun) in the class (pronoun).
Thus, the options (d), (b) and (a) are incorrect.
In the above case, “smart” is “predicate adjective” used to describe nature of students (noun) in the class (pronoun).
Therefore, the correct option is – d. The students in my classes are smart.