One must defend . . . . . . . . against bullies. A. herself B. themselves C. oneself D. ourselves

The correct answer is C. oneself.

The word “oneself” is a reflexive pronoun that refers to the person who is speaking or acting. In this case, the speaker is saying that they must defend themselves against bullies.

The other options are incorrect because they do not refer to the person who is speaking or acting. Option A, “herself,” refers to a female person. Option B, “themselves,” refers to more than one person. Option D, “ourselves,” refers to a group of people that includes the speaker.

In this case, the speaker is only referring to themselves, so the correct pronoun is “oneself.”