A. Provides backing music to the main melody is a description of an accompanist's responsibility.
An accompanist is a musician who provides musical accompaniment to a soloist, singer, or other musicians. Their primary role is to provide backing music that supports and enhances the main melody or vocals, rather than playing the main melody themselves. The accompanist may play an instrument or sing, and must be able to follow the soloist's lead and adjust their playing to match the tempo, dynamics, and style of the main performer.