You conduct a study of romantic love among college students. you ask one student to participate, and she says she is annoyed and offended that you asked her. you have caused her harm, but does this level of harm constitute an ethics violation?

No, because this harm is not greater than that which people encounter in everyday life.
When researchers tried to conduct a research through questionnaire, it is very common for the researchers to meet the test subject that would feel uncomfortable about the questions.
In this case, as long as the researchers do not force the subject to continue the research, the researchers couldn't be considered to have crossed any ethical line.

Ithink it's c selection but i don't really know.