If two variables are inversely proportional, then when one increases, the other decreases, and vice versa. If a variable, y, is inversely proportional to a variable, x, then y = k/x, where k is the proportionality constant.
The question in choice-C is the correct answer to your question.
(Is this confusing ?)
Explanation:
it is almost zero .this is because the distance and the electrostatic force are inversely proportional