We need to choose the correct grammatical structure.
Let’s test each one:
- (A) "Is a professional pianist'' – grammatically correct, sounds smooth.
- (B) "Played the piano professionally'' – tense doesn’t match "plays'' in the first part.
- (C) "Plays the piano professionally'' – repeats "plays'', sounds odd.
- (D) "Is professional pianist'' – missing article "a'', so grammatically incorrect.
Thus, Option A fits both grammar and meaning.