Answer: Option (a) is the correct answer.
Explanation:
The gravitational pull of the Earth is known as force of gravity. Basically force of gravity attracts any object with mass towards itself.
Therefore, when an acorn falls from a tree then we can say that it falls because of the gravitational pull acting on it.
Thus, we can conclude that out of the given options, the statement force of gravity is acting on the acorn is true.
