Which description correctly identifies an OR gate?

• A. Outputs a difference of inputs
• B. Inverts the input
• C. Outputs true when any input is true
• D. Outputs true only when both inputs are true

Answer: (C)

An OR gate outputs true when any input is true. Think of two switches in parallel controlling one light: if either switch is on, the light comes on, and if both are on, the light is still on. Only when both inputs are off does the output stay off. This is what the described option means by “outputs true when any input is true.”

This differs from inverting a signal (NOT), which flips the input; it also differs from an AND gate, which needs both inputs to be true to produce true; and it isn’t describing a function that outputs true only when exactly one input is true (that would be a different gate).