Which gates are opposite of one another?

The correct answer is that XOR and XNOR gates are considered opposites of one another. XOR (exclusive OR) produces a high output (true) only when the number of true inputs is odd, typically when exactly one of its two inputs is true. In contrast, the XNOR (exclusive NOR) gate, which is the complement of the XOR gate, produces a high output when the number of true inputs is even, primarily when both inputs are the same. This inherent relationship makes the XOR and XNOR gates opposites in terms of the logic they represent.

In terms of the other options, while AND and OR have distinct functions in logic operations, they do not exhibit this direct opposite relationship. NAND and NOR gates are both negative forms of their respective AND and OR gates, but they are not opposites of each other in the same way that XOR and XNOR are. NOT and AND are also not opposites; rather, NOT is a unary operation that inverts the input, whereas AND operates on two inputs. Therefore, the unique relationship between XOR and XNOR in producing opposite outputs under the same conditions highlights why they are classified as opposites in the context of logical operations.