1. Japan attacked Pearl Harbor to limit the ability of the United States to mount a strong resistance to Japanese expansion in Asia and the Pacific. Option D is correct.
2. During World War II, the United States and the Soviet Union were united in their opposition to Nazi Germany. Option A is correct.
In spite of the fact that relations between the Soviet Union and the United States had been strained in the years before World War II, the U.S.-Soviet alliance of 1941–1945 greatly cooperated and was fundamental to defeat the Nazi Germany.