GATE 2024 · CS1 - Forenoon
Consider a digital logic circuit consisting of three 2-to-1 multiplexers M1, M2, and M3. X1 and X2 are inputs of M1 (X1 on select-line-value 0, X2 on select-line-value 1), producing output Q1. X3 and X4 are inputs of M2 (X3 on 0, X4 on 1), producing output Q2. A, B, and C are select lines of M1, M2, and M3, respectively. M3 takes Q1 on its select-line-value 0 input and Q2 on its select-line-value 1 input, and produces output Y.
For an instance of inputs X1=1, X2=1, X3=0, and X4=0, the number of combinations of A, B, C that give the output Y=1 is _________