What should $($i$),($ii$)$ be for the circuit to represent the sum of a full$-$adder circuit?

$($i$)$ C$($ii$)$ C$\text{'}$

$($i$)$ C$\text{'}($ii$)$ C$\text{'}$

$($i$)$ C$\text{'}($ii$)$ C

None of the others

$($i$)$ C$($ii$)$ C