Correct Answer: Something that can happen very fast without hesitation.

Solution : The correct choice is the third option .

Explanation:

The idiom at the drop of a dime is used to convey the idea that something can happen instantly or with very little notice. It emphasises quick and immediate action without any delay or hesitation. The idiom suggests a sudden and prompt response to a situation.

Therefore, the correct meaning of the idiom is something that can happen very quickly, without hesitation.