Question

The state transition diagram for the logic circuit shown is

Answer 1

When A = 1, then Q will be selected by MUX and feedback to D flipflop which gives output Q again.
So at A = 1 it holds its state. When A = 0, then $\overline{Q}$ will be selected by MUX and feedback to D flipflop and output will be Inverted. So for A = 1 it holds the state and for A = 0, it interchanges the state i.e. if Q = 0 then it will go to Q = 1 and if Q = 1 then it will go to Q = 0, So option (d) is correct.