Trying to regulate or sanction someone's words is known as which of the following?

Libel

Slander

Defamation

Censorship

This one is kinda hard ... a lot of these words are synonymous to each other but I think it's defamation I'm not sure though

Trying to regulate or sanction someone's words is known as censorship.

Explanation:

Censorship is the suppression of speech or the removal of music, art or communication material which is considered to be critical, harmful or sensitive by a censoring authority. It is used to promote social, party or other group interests.

Censorship usually refers to publicly communicated opinions, but in times of non-freedom, private communication is also controlled. Censorship also involves criminalizing those who try to circumvent censorship. Censorship has been part of the practice of power structures for virtually all of human history.