My understanding is those are the rules for
automatic approval of a clearance and if you respond with drug use then you will be initially denied and then they will take a look at your specific circumstance.
Marijuana usage is so pervasive that they basically can't exclude anyone who's ever used it, instead they want to see that it's been at least a year (preferably more) since you've used it and you will probably get approved. "Harder" drugs they are more strict on.
If you just smoked pot in college no worries, you'll be fine.