The diagram represents the "NOT" logic gate.
So, Option (C) "NOT" is the correct answer.
Logic Gate: "NOT"
One-input, one-output gates are the most basic type of gate.
In the opposite case of the input, the output is 1. Because of this characteristic, a NOT gate has occasionally been termed an inverter.
The Boolean formula Y=A' can be used to determine the output when there is just one input, A.