$\sim$(P $\rightarrow$ Q)
= $\sim$( (P $\rightarrow$ Q) ^ (Q $\rightarrow$ P) )
= $\sim$ ( ($\sim$P v Q) ^ ( $\sim$Q v P) )
= $\sim$($\sim$P v Q) v $\sim$($\sim$Q v P)
= (P ^ $\sim$Q) v (Q v $\sim$P) = P$\bigoplus$Q
Using distributive law. (a + bc) = (a + b).(b + c)
= ( (P ^ $\sim$Q) v Q) ^ ( (P ^ $\sim$Q) v $\sim$P)
= ( ( P v Q)^($\sim$Q v Q)) ^ ( ( $\sim$P v P) ^ ($\sim$Q v $\sim$P) )
= ( ( P v Q) ^ ( $\sim$Q v $\sim$ P)
Now here we have two choices.
1. ($\sim$P $\rightarrow$ Q) ^ ( Q $\rightarrow$ $\sim$P) = $\sim$P $\leftrightarrow$ Q
2. ($\sim$Q $\rightarrow$ P) ^ (P $\rightarrow$ $\sim$ Q) = P $\leftrightarrow$ $\sim$Q.
So both 1 and 2 option is correct.