If we want to replace the XOR gate with a $2-$to$-1$ Multiplexer. The functionality of the circuit must not change. The data inputs $d_0,d_1$ and the select input $S$ of the MUX will be respectively

a$.B_i,B_i,M$

b$.B_i\frac{,}{b}ar(B{)}_i,M$

c$.\frac{?}{\text{b}\text{a}\text{r}}(B{)}_i\frac{,}{b}ar(B{)}_i,M$

d$.\frac{?}{\text{b}\text{a}\text{r}}(B{)}_i,B_i,M$

Clear my choice