One of the biggest health risks of drug use is addiction. Although initial drug use might be abuse can alter gene expression and brain circuitry leading to addiction. This involves compulsive drug cravings
and use - sometimes at any cost.

cancer
dependency
infectious disease

More than 600. i'm just guessing

Ibelieve it would be d (side effect) sorry if i'm wrong(:

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)