The Cities of Longview and Richland,in Washington,are Unique Because of What

The cities of Longview and Richland,in Washington,are unique because of what?

A) They are both centers for the nuclear energy industry.
B) They were both preplanned cities.
C) They were both towns owned by private corporations.
D) They are both owned and run by Native American tribes,while remaining part of the United States.