Question

what was the role of the manhattan project during wwii?
securing new york from invasion
atomic weapons development
military administration oversight

Explanation:

The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. It was not about securing New York from invasion (that was a misnomer - the name "Manhattan Project" was just a cover name, not related to New York's defense in that sense) or military administration oversight in a general sense. Its core was the development of atomic weapons.

Answer:

atomic weapons development