According to the source, what is the ethical problem of dropping an atomic bomb?

On December 7th, 1941 Pearl Harbor, Hawaii was the target of an unannounced military attack by the Japanese Navy. This resulted in the United States entry into World War II.

After almost 4 years of war, 400,000 US casualties, 6 months of air strikes on Japanese cities and an impending defeat of Japan, an ultimatum was delivered to Japan by the United States: surrender or be destroyed. On August 6th, 1945 the United States military dropped the first atomic bomb as an act of war on the Japanese city of Hiroshima.

Explanation:

i am speed running these questions like it is

( sorry my answer is short they wont let me do just war so ignore this) xd

d is the best answer for this question.