For the logic circuit shown in the original figure, the output Y is zero for which input combination?

Question

G1 Physics · Accepted Answer

From the gates in the source diagram: Y₁ = AB. The lower OR-gate input combination gives Y₂ = A̅ + B. The final gate is NAND, so Y = overline(Y₁Y₂). Evaluating the four input combinations gives the source truth table: 00→1, 10→1, 01→1, 11→0. Thus Y=0 only for A=1, B=1. Correct option: A.