What kind of injury is caused by written material that harms a person's character?

The correct choice is libel, which refers specifically to written or published statements that falsely harm a person's reputation or character. In legal terms, for a statement to qualify as libel, it must be untrue, published, and must cause demonstrable harm to the person’s standing in the community.

Assault is related to threats or attempts to cause physical harm, which does not pertain to written material. Slander, while similar in that it involves damaging someone's reputation, refers specifically to spoken defamatory statements rather than written ones. Invasion of privacy deals with a person's right to keep their private life out of public view and is not directly connected to harming a person’s character through written material. These distinctions clarify why libel is the appropriate answer, as it directly addresses the context of written defamation.