WAEC Computer Studies 2019 Paper

Concept:A NAND gate gives output 0 only when all inputs are 1; otherwise it gives output 1.Explanation:A NAND gate is the NOT of an AND gate.Let the inputs be $A$ and $B$. Then the output is $Y = \overline{A \cdot B}$.For an AND gate, $A \cdot B = 1$ only when all inputs are 1.Therefore, $\overline{A \cdot B} = 0$ only when all inputs are 1.So, the output of a NAND gate is 1 whenever all inputs are not 1.In other words, the output is 1 when at least one input is 0.This condition is exactly “any of the input is 0”.Answer:C. any of the input is 0.