The correct option is (C)!
Sum $= x⊕y⊕z = x⊙y⊙z$
Carry $= zx + zy + xy$
When there are odd number of inputs then EXOR and EX-NOR gives the same truth table, as EXOR is an ODD function it means if there are odd number of 1's in the input then the output is 1, and EXNOR is an even function, it means if there are even number of 0's in the input then output will be 1.