For an n - variable Boolean function maximum number of prime implicants is

In a half-subtractor circuit with X and Y as inputs, the Borrow (M) and Difference (N = X - Y) are given by

The outputs of the two flip-flops Q₁, Q₂ in the figure shown are initialized to 0, 0. The sequence generated at Q₁ upon application of clock signal is

In the circuit shown, choose the correct timing diagram of the output (y) from the given waveforms W₁, W₂, W₃ and W₄.