Final answer:
The cognitive triad theory by Aaron Beck emphasizes negative beliefs about oneself, among other factors, contributing to the development of depression. Correct option is C.
Step-by-step explanation:
The correct answer is C) Oneself. Aaron Beck, a prominent cognitive psychologist, developed the cognitive triad theory which suggests that an individual's negative beliefs about oneself, the world, and the future contribute to the development of depression. The cognitive triad emphasizes negative self-perceptions or beliefs about oneself.