Anwer is (B)
C is not belonging to any set,as it is not given anything than generally we assume like this usually!
now |x| = |y| (Push x till 'c' appear and than pop 1 'x' for every 1 'y'
Here, x != yR (If it is x != xR or y != yR, than we need comparison but there is no need for comparison here!)
So, answer is (B) and if we assume that x,c,y all belongs to Sigma* than answer would be (A)