When the input terminal of the NOT gate is at _______, it is termed as logic 0.

Correct option is A

When the input terminal of the NOT gate is at 0 V, it is termed as logic 0. A NOT gate in digital logic operates such that a 0 input (0 V) gives a 1 output, and a 1 input (usually represented by 5 V) gives a 0 output.