Answer :
I would assume Gravity because gravity can pull down mass
Answer: Option (b) is the correct answer.
Explanation:
An object which acts on the mass of an object or pulls an object towards itself in the downward direction is known as gravity.
For example, an apple falling from tree on the surface of earth depicts that due to force of gravity applied by earth the apple falls on it.
It is a natural force and value of a gravitational acceleration is 9.8 m/s.
Thus, we can conclude that a force that causes mass movement is called gravity.