The question is an analogy of the form
A : B : : C : D, where the relationship between the first pair must be repeated in the second pair.
In the first pair, a
Play is performed by an
Actor, i.e. the second term is the person who performs the first.
Applying the same relationship, a
Concert is performed by a
Musician.
A percussion, a symphony and a piano are things used or played in a concert, but they are not the performers of the concert.
Hence, the correct answer is
Musician, i.e. option C.