Read a paragraph from an essay supporting Truman’s decision to use the atomic bomb against Japan.

[1] Many people have argued that nothing could justify the president’s use of the atomic bomb because it killed so many innocent civilians. [2] Truman himself refused to drop a third atomic bomb on Japan because he was horrified by the death and devastation it had caused. [3] However, he never regretted his decision to use it in the first place. [4] Using the bomb brought an immediate end to a war that might have gone on for months or even years longer.

Which sentence states a reason?
sentence 1
sentence 2
sentence 3
sentence 4