Correct option is A
The Manhattan Project was a research and development program during World War II, led by the United States with support from the United Kingdom and Canada. It aimed to develop the first nuclear weapons. The project resulted in the creation of atomic bombs, which were later dropped on Hiroshima and Nagasaki in 1945. The success of the Manhattan Project fundamentally changed the course of warfare and geopolitics in the 20th century.
Thus, the correct answer is (a) A research and development undertaking that produced the first nuclear weapons.
