which one of the following sentences contains a predicate adjective?

A. I bought my lunch for the first tim this year.

B. The teacher appeared angry when Dave forgot his homework.

C. what does this hard lesson teach you?

D. We scanned the distant shore for signs of life.

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.