Answer:
There are three correct answers to the question:
Only a small number of people lived in the area.
The Grand Coulee Dam provided a source of power.
The Columbia River provided a great deal of cold water.
Step-by-step explanation:
Hanford Nuclear Reservation in its first years was a unit of the Manhattan Project, the creators of the atomic bomb. There was produced plutonium that was used in the first atomic bomb produced by the country.
Its site in Hanford was chosen because it wasn't very populated which helped to decrease risks in the event of an accident. Being near the Grand Coulee Dam helped with the electricity that would be needed and the water from the Columbia River was could enough to help with plutonium production.