Correct Answer: Blunder

Solution : Given:
Quarrel is related to War.

Here, the second term is the synonym of the first term –
Like in, a Quarrel is related to War – A Quarrel means a heated argument or disagreement and war means a state of armed conflict between different countries or different groups within a country. Therefore, both means to fight against something.
Similarly, Error is related to ___ – An error means mistake and the synonym of the error is a blunder.

Therefore, a blunder is related to an error. Hence, the third option is correct.