What does the phrase gravitational pull mean as it is used in the text?

Because meteors are so small, they often get pulled into planetary orbits, while asteroids and comets are large enough that they stay within the gravitational pull of the sun.

1. A force that pushes one thing away from another
2. Something that makes an object stay on the ground
3. Something that pulls an object strongly downward
4. The force of one thing pulling another thing closer