Case1: if m is even then n=k number of b’s = number of c’s. Therefore X and Y both must represent pop operation.
Case2: if m is odd then no constraint number of b’s,number of c’s just that c must come after b. from state Q5 to Qf there is move for which b must be in the stack, so we cannot push c into stack and must ignore c. Therefore W and Z both must represent ignore operation i.e do nothing with stack.
Hence, Option B is correct.