Век живи, век учись

As part of the strike training I have to take defensive driving courses because some homicidal maniac is planning to have me drive a company truck around NY. The courses are theoretical, on-line, no actual driving involved and can be taken during conference calls. The contents are mostly common sense and one can easily guess the answers to the end-of-chapter quizzes. I had no problems with all but one section. Without any sort of explanation you are provided with a list of symptoms and get asked what causes these: depressants, stimulants, narcotics and drugs, or marijuana and hashish. Now, these people just explained in detail the difference between wet, slippery and dry road, but this I am supposed to just somehow know from ... what, personal experience? How does one correctly answers this without having the first hand acquaintance with the substances in question? I sort of managed to guess the difference between reactions to depressants and stimulants, but the rest of it... I can't even understand why they separate narcotics/drugs and marijuana/hashish into two categories. And why not cocaine and, oh, I don't know, something else.

Two interesting facts from the course:
1. I fall into the category of middle-aged drivers.
2. Up till now I didn't know how to spell either marijuana or cocaine.