It's pronounced "ensemble" by the way. And, one way that a pianist would have a role would be by being in the background as an example and playing his part. He's going to play what he needs to play. The question does seem a little to vague, but truly, I would say simply, that the person who is playing it, just plays his part as they all make music sound good.
C. characteristics feature that distinguishes the character or feel of the music
It basically means to spoil carefully laid plans, For example;
"Don't upset the apple cart by revealing where we're going."
The answer would be
<em>They placed closer objects lower.</em>
Hoped this helped:)
