$($a$)$ Express the Boolean function Y in terms of A$,$ B$,$ C$,$ and D$.(5$ pts$)$

$($b$)$ Which inputs will give the highest VOL, and which input will give the lowest VOL? $(5$ pts$)$

$($c$)$ In order to ensure that the highest VOL in part $($b$)$ is sufficiently low, should kn be greater than or smaller than kp$?(5$ pts$)\text{'}$