Question

what is the primary cause of rainstorms?
earth is heated by the sun.
mountains direct moist air upward.
water forms droplets when cooled.
most of earth is covered with water.

Explanation:

To determine the primary cause of rainstorms, we analyze each option:

• "Earth is heated by the Sun": Solar heating drives the water cycle, including evaporation of water. Warm, moist air rises, cools, and condenses to form clouds and eventually rain. This is the fundamental energy source for the processes leading to rainstorms.
• "Mountains direct moist air upward": This is orographic lifting, a local factor that can cause rain but not the primary cause of rainstorms in general.
• "Water forms droplets when cooled": This describes condensation, a part of the process, but it's a result of air cooling (often due to solar - driven processes like air rising), not the primary cause.
• "Most of Earth is covered with water": This provides the water source but doesn't explain the process that leads to rainstorms. The heating of the Earth by the Sun initiates the evaporation - condensation - precipitation cycle that is the basis of rainstorms.

Answer:

A. Earth is heated by the Sun.