How did the “Manhattan Project” change the world?

The Manhattan Project had launched the Atomic Age. Since then, the world's nuclear arsenal has grown to about 15,000 weapons, many with power exceeding the atomic bombs of World War II. Most Manhattan Project workers built and operated the uranium enrichment facilities and reactors. In addition to developing the atomic bomb, the Manhattan Project was charged with gathering intelligence on the German nuclear energy project.

(d) take jobs from american workers.