After World War II, the U

After World War II, the U.S. Government spent two decades investigating UFOs because they

A) were themselves developing new types of aircraft and used the official investigation as a cover-up
B) thought that they might be new types of aircraft being developed by the Soviet Union
C) knew that UFOs were alien craft and used the official investigation as a cover-up
D) were afraid that an alien civilization was in the process of invading the Earth