A hospital safety manual details which materials are considered hazardous and nonhazardous. Which is considered a hazardous material?
water
food
medicine
blood

Iwould say c. take responsibility for your behavior

Ibelieve this would be an obstacle.

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)