Answer:
The answer is static friction. This is the friction that involves objects that do not move.
Explanation:
Friction is a force which opposes the motion of one object moving relative to another. static friction and kinetic friction are the two type of friction.
Static friction is that type of friction which keeps an object at rest. Force must be applied greater than static friction to move an object. Therefore it is the static friction which helps the pile of rocks from falling apart.
(Brainiest and thanks appreciated)
