Which binary operation is true if one of two inputs is true but not both?

The concept being tested here is the logical operation known as "exclusive or," commonly represented as XOR. This operation returns true only when exactly one of the inputs is true—meaning that if one input is true and the other is false, the result is true. However, if both inputs are true or both are false, the result is false.

This is in stark contrast to the other operations listed. For example, the AND operation returns true only when both inputs are true, while the OR operation returns true if at least one of the inputs is true, irrespective of the other. The NAND operation, on the other hand, is the negation of AND and thus returns true when both inputs are not true.

The specific condition highlighted in the question, where only one input can be true and not both, is the defining characteristic of the XOR operation, making it the correct answer. Understanding this operation is crucial, especially in contexts like digital logic design and computer security, where accurate decision-making based on binary conditions is essential.