Predicate adjective relates to subject of the sentence, and modifies it.
In A the subject is I, adjective "first" does not relate to it.
In B the subject is The teacher, "angry" is an adjective which relates to it, and modifies the subject.
In C the subject is You, adjective "hard" does not relate to it.
In D the subject is We, adjective "distant" does not relate to it.
So B is true.
