A college student has been assigned to write captions for a new textbook on gravity and motion. This is one of the pictures from the textbook. Earth, the moon, and the orbit of the moon around Earth. The moon has one arrow pointing toward Earth, and one pointing down away from Earth.

Which caption best describes the thinner arrow?

The moon moves toward the Sun due to gravity.
The moon will move away from Earth because of inertia.
The moon would move in a circular path if there were no forces.
The moon would not stay in orbit without the pull of Earth's gravity.