We want to implement a four$-$input function with a multiplexer. The available multiplexer is the $8$ by $1.$ The available that we have is:

Here is the truth table of our fonction:

A B C D Y

$00000$

$00011$

$001$

$01$

$01010$

$01100$

$01110$

$10000$

$10010$

$10100$

$10111$

$11001$

$11011$

$11101$

$11111$