Is the underlined word a predicate nominative or a predicate adjective?

Those bananas might still be tasty, but they are becoming mushy.

a. predicate adjective

b. predicate nominative

Assuming the underlined word is either 'tasty' or 'mushy', either way the answer is A, it is a predicate adjective. Because that word following the linking verb (either be, or are) is an adjective, therefore it cannot be nominative, because those are nouns.