Parents who disguise hostility toward their children by becoming overly protective of them are very likely using the defense mechanism of

The answer is: D) Reaction formation

In defense mechanism, reaction formation refers to the act of hiding our true intention/impulse by acting in the opposite direction in an exaggerated manner.

Parents who are hostile to their children tend to use 'protecting'the child as an excuse to hide their true intention in order to avoid judgement from other people.

For examples, let's say that there is a parent who want her daughter to be a famous pianists despite her daughter interest in athletic sports. So, the parent decided to use hostility and banned her daughter from training and say that 'I'm trying to protect her from physical harm'