JAMB Computer Studies 2022 Paper

Concept:A NAND gate outputs $1$ whenever at least one input is $0$.Explanation:The NAND operation is the opposite of the AND operation.For a two-input NAND gate, $Y = \overline{A \cdot B}$.If any input is $0$, the AND result is $0$, so $\overline{0} = 1$.For example, $A = 1$ and $B = 0$ gives $Y = \overline{1 \cdot 0} = \overline{0} = 1$.The output is only $0$ when all inputs are $1$: $Y = \overline{1 \cdot 1} = 0$.Therefore, the output is $1$ whenever a $0$ is present at an input.Answer:A. whenever a 0 is present at an input.