Suppose that $f(x,y,z)=(0,1,6)$ is being implemented using $4-$to$-1$ Multiplexer with $x$ and $y$

being connected to $s_1{s}_0$ respectively. Then the MUX data inputs will be

a$.,I_0=0,I_1\frac{?}{b}=ar(z),I_2\frac{?}{b}=ar(z),I_3=z$

b$.I_0\frac{?}{b}=ar(z),I_1\frac{?}{b}=ar(z),I_2\frac{?}{b}=ar(z),I_3=0$

c$.I_0=1,I_1=0,I_2=0,I_3\frac{?}{b}=ar(z)$