Earth is heated by the Sun. Mountains direct moist air upward. Water forms droplets when cooled. Most of Earth is covered with water.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: What is the primary cause of rainstorms?
Possibilities:
- Earth is heated by the Sun.
- Mountains direct moist air upward.
- Water forms droplets when cooled.
- Most of Earth is covered with water.

Earth is heated by the Sun.