When it comes to cyberbullying, “power imbalance” is the term used for pretending to be someone else online.
repeatedly following someone around online.
intimidating someone online with threats.
repeatedly annoying someone online.

Option C (intimidating someone online with threats) is the right choice.

Explanation:

To stalk, threaten as well as scare others, cyberbullying would be the use of cellular telephones, text messaging, e-mail, discussion boards, or online media networks such as Instagram as well as Twitter. The involvement of power imbalance throughout cyberbullying mostly in the existence of many teens, conventional bullying, described as an offensive behavior that's also replicated against a target of lower proportion, is a significant issue.

Some other suggestions made aren't relevant to the circumstance in question. So, the solution here is just the right one.