The teacher gives a link so you can watch the video again. I know of Jared Diamond from his books. I have not seen this video before & would need to watch it too in order to help you.
The correct answer is letter b. 50 percent.
Part of the process of being an adolescent is understanding one's self, sometimes adolescents becomes passive in terms of seeking their own identity and that state is called Identity Diffusion. Identity Diffusion refers to the state of an adolescent, who has not understood or figured out who they truly are.