Ballistic stretching is best performed
a. before intense workouts
b. after a thorough warm-up
c. weekly
d. never

The best answer is D. Ballistic stretching is best performed never. This kind of stretching is a passive or a dynamic form stretching in a bouncing motion. This type of stretching is not recommended by the American Academy of Orthopedic Surgeons since it has been linked to injury. The stretches force the limb to a extended range of motion. It can cause serious injuries.

Ican only answer your first question, a machine is like a human body because it's a little similar. they both almost work like the same.