$\underline{\text{In General}}:$
$\text{For implimentation of MUX using Decoder, the no. of Input lines of MUX must be SAME as no of Output lines of Decoder}.$
$\text{i.e N = $2^{k}$ }$
$\text{In $2^{k} \times 1$ MUX, for $2^{k}$ no of Inputs, total $2^{k}$ multiplications & 1 Addition needed to convert them into single Output Line}.$
$\text{∴ $2^{k}$ AND Gates & 1 OR gates needed. }$
$\underline{\textbf{This is Implimentation of $4\times1$ MUX using $2\times4$ Decoder }}:$
$\underline{\textbf{Correct Ans}}: \text{Option A, C}$