(a) p $\rightarrow$ q, we can write ˥p ˅ q, so the option is (iv)
So the answer could be 3 or 4, now check for 4 and by solving, we will get:
(b) p ˅ q = ˥(˥p)˅q = ˥p$\rightarrow$ q,
so the option is (iii), we can say by checking the given options that the answer is 4, but for the sake of proof:
(c) p ˄ q = q ˄ p = ˥(˥q ˅ ˥p) = ˥(q $\rightarrow$ ˥p) , so the option is (i)
(d) p ˄ ˥q = ˥(˥p ˅ q ) = ˥(p$\rightarrow$q) , so the option is (ii)
So, the correct answer will be (4)