What does a truth table for a NAND gate look like?

A truth table for a NAND gate reveals its behavior based on the values of its inputs. The correct answer identifies that the NAND gate outputs false only when both inputs are true. This means that in all other combinations of inputs, the output will be true.

To illustrate this, consider the scenarios with two inputs, A and B:

• When both inputs A and B are true (1), the NAND gate produces an output of false (0).

• If either input A or input B is false (0), or both are false, the NAND gate outputs true (1).

This behavior directly corresponds to the definition of a NAND gate, which states that it is the negation of the AND operation. This unique feature distinguishes it from other gate types and highlights its versatility in digital circuits, where it is used to create more complex logic functions.

The other options do not accurately describe the behavior of a NAND gate. For instance, saying that it outputs true unless both inputs are false misrepresents the NAND function. Similarly, the idea that it outputs true when at least one input is true does not align with the condition under which it produces an output of false. Thus, option B stands out as the only correct description of a NAND gate's output.