Answer:
Regression
Step-by-step explanation:
Regression is a defense mechanism that is used to defend themselves from anxiety, depression, etc. This defense mechanism was developed by Anna Freud.
In this mechanism, the ego revert to the earlier stage of the defense mechanism. This mechanism works with the retreat and enabling a person psychologically to the time in their early period when the person feels safer.
For instance, a child starts to suck their thumb again and to wet the bed again when he needs to spend time in the hospital.