Precipitation is water that falls to the Earth through rain, snow, sleet, or hail. As the water reached the Earth's surface it may become ground water stored in aquifers, or if the Earth can no longer hold the water it becomes runoff. The water then flows back into the Earth's different bodies of water.
The answer is D. A set of diary entries written by generals who planned strategies during world war II. This is a primary source which was written during that time period and so would be the best support for the authors' argument..
