The correct answer to your question would be D.
The Rape of Nanjing was significant because of the sheer volume of people who were massacred, because it was actually a direct act of manipulation and terrorism, these two things made also the United States more attentive towards the happening in the Pacific as it saw that the Japanese had an increased growth in influence over this region.
The answer to this question is A. Jet streams
Jet streams are located near the altitude of the upper troposphere. It's a movement of wind that travels from one side of the planet hemisphere to another. The movement of jet streams will bring up different temperature of air which could influence the weather that exist in certain regions.