If im correct the answer should be Submarines and mines were an inexpensive and better way to engage battleships. I hope this helps. let me know if it doesnt
Answer: The Manhattan Project was the code name for the American-led effort to develop a functional atomic weapon during World War II.
Explanation: The Manhattan Project was the American program for researching and developing the first atomic bombs. The weapons produced were based solely upon the principles of nuclear fission of uranium 235 and plutonium 239, chain reactions liberating immense amounts of destructive heat energy.
The answer for your question is D
