Correct Answer: To avoid saying something

Solution : The correct answer is the third option.

The idiom "Bite your tongue" is used to express the idea of refraining from speaking, especially when one has an urge to say something that may be inappropriate, hurtful, or controversial. It implies exercising self-restraint and keeping quiet in a situation where speaking out might cause trouble or offence.

Therefore, the correct answer is to avoid saying something.