Which sentence uses a predicate adjective?

A. Students should recognize the importance of getting a good night's sleep. B. The reason for his absence is quite simple to understand.

C. You are the only person who can know if you succeeded.

D. The only true critic of your work is you.

The correct answer would be option B. The sentence that uses a predicate adjective is this: The reason for his absence is quite simple to understand. The predicate adjective in this sentence is "quite simple" and this describes the noun and the subject of the sentence "reason". Hope this answers your question.