When using a digital circuit, which gate produces a true output when at least one input is true?

The OR gate is a fundamental component in digital circuits known for its ability to produce a true output when at least one of its inputs is true. This means that if any of the connected inputs carry a high signal (true, which is often represented as a binary '1'), the output of the OR gate will also be high. This characteristic makes the OR gate particularly useful in scenarios where a system needs to respond to multiple conditions or inputs.

In contrast, the AND gate requires all of its inputs to be true for the output to be true, meaning it only outputs a high signal when every input is high. The NAND gate, which is essentially the opposite of the AND gate, produces a false output only when all of its inputs are true. The XOR gate, or exclusive OR gate, outputs true when the number of true inputs is odd, specifically when one input is true and the other is false, but not when both are true.

Thus, the OR gate's direct relationship to having at least one true input is what makes it the correct answer for the question posed.