Approach an adult such as a high school counselor. Inform them of the situation. Then, after the adult consults with the friend, I would approach him/her and help them out with whatever they are going through. I'd tell them that I'm there for them and try to help to get them to stop.
I dunno and I know what you’re thinking
Answer:
It should be C, That's what I learned back then.
I'm pretty sure its B. I am not 100% positive, but it sounds correct to me. Please let me know if I am correct or not and I really hope this helps.