ANSWER
Gravity pulls objects towards the center of the earth.
Step-by-step explanation
We want to identify the correct option.
Gravity is an attractive force that acts on an object due to another object due to the masses of the objects. Gravity works by pulling one object towards the center of the other object.
Gravity is a non-contact force. This implies that the two objects do not need to touch one another before the force of gravity sets in.
Therefore, going by these, we see that the only option that can be correct is the first option. i.e. Gravity pulls objects towards the center of the earth.