Composition is a short, recurring melodic or rhythmic idea that provides unity in a musical piece.
a) true
b) false

B) False

A composition in art/design are multiple  elements combined together for a purpose.

For music I think it is true.

"Musical composition, or simply composition, can refer to an original piece or work of music, either vocal or instrumental, the structure of a musical piece, or to the process of creating or writing a new piece of music. People who create new compositions are called composers."

Let me know if this was confusing or not.