the answer is C. thinking about a problem constantly
If this is a true/false question, the answer is true.
Wdym my cool homeslice dood>??
You could say something along the lines of:
"Hey, Friend, what's so good about weed? Why are you always smoking it?"
If he's smoking it for medical purposes, then just drop it, but if it's illegal and he's doing it to "look cool", then I would further ask questions about it.