Answer the following question given this paragraph: 

The outer planets in the solar system are giant balls of swirling gas. Earth and the other inner planets are relatively small, dense, and rocky. Most of Earth’s surface is covered with water. As far as we know, Earth is also the only planet that has liquid water. Earth's atmosphere has oxygen. The water and oxygen are crucial to life as we know it. Earth appears to be the only planet in the solar system with living creatures. You can learn more about the planets in the Our Solar System chapter.


Q: What is most of earth's surface covered with?

 Choices:

- insects

- sand

- silicon

- water

A:
water
