What role does a conductor play in an ensemble?

The role of a conductor in an ensemble is primarily to guide the performance and maintain the tempo. Conductors provide visual cues to the musicians, using gestures to indicate dynamics, tempo changes, and entrances for different sections or instruments. This ensures that all the performers are synchronized, which is crucial in ensemble playing.

A conductor's ability to interpret the music and communicate that interpretation to the ensemble helps shape the overall sound and expression of the piece being performed. This leadership is pivotal in large groups, where coordination among various sections, such as strings, brass, woodwinds, and percussion, is essential for a cohesive performance.

In contrast to other roles mentioned, conductors do not perform solo pieces, compose new music, or typically play an instrument during the performance. Their primary focus is on directing the ensemble, making option B the correct choice.