The correct answer is: The amount of water vapor in the air.
Explanation:
Humidity is basically the amount of water vapor that's i the air.
1) The amount of precipitation that falls. This wouldn't be the correct answer.
2) The temperature of air that causes condensation. This answer is also incorrect.
3) The amount of water vapor in the air. This answer is correct because, Humidity is the amount of water vapor that is in the air.
4) The condensation that forms on a cooler surface. This answer isn't correct because, Humidity is the amount of water vapor that's in the air not collected on cool surfaces.
