Which potent form of cocaine is named for te popping sound it makes when burned?

Crack is a potent form of cocaine that got its name from the popping sound it  makes when you burn it.

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)