I'll give you a question, please answer with step-by-step reasoning process.
He played the bass fiddle professionally, but for his baby he used it to play a fun simple what?\nOptions:\n- music\n- jazz band\n- orchestra\n- nursery rhyme\n- music store

nursery rhyme
Nursery rhymes are traditional poems for children.

Poems for children are fun and simple.

.

Therefore, the answer is nursery rhyme