What is meant by the phrase “breaking a habit”?
to perform a behavior more frequently than normal
to give less priority to a repeated behavior
to understand why you exhibit a particular behavior
to stop doing a particular behavior for good

The correct answer is the fourth option.

To break a habit means to stops doing a particular behavior for good. A habit is something that you do repeatedly or often, some are harmless such as cracking your knuckles whereas some can be harmful to you such as smoking. If you break a habit you put an end to it, you make a conscious decision and effort not to do it anymore.