Correct option (D) Input A is connected to bar Q1
Explanation:
The input of D2 flip-flop is
D2 = bar Q1s + Q1S(∵ A = Q1)
The alternate expression for EX-NOR gate is = bar(A ⊕ B) = A ⊕ B = A ⊕ B
So, if the Ex-OR gate is substituted by Ex-NOR gate then input A should be connected to bar Q1
D2 = bar Q1S + Q1S = Q1S + Q1S
(∵ A = bar Q1)
= QiS + bar Q1.S