Answer:
B. to open China to trade
Step-by-step explanation:
China was a very closed country, and it was not fond at all in engaging into trade with the rest of the world. The Western colonial powers were the total opposite. They were engaging in trade across most of the world, making a lot of wealth from this.
The colonial powers didn't liked the idea that China had such great potential and so many things to offer, but it was closed to the world, and particularly to them. This led to military intervention by the colonial powers, and they managed to win in the conflict.
The end result was that China lost pretty much all of its ports, as the coastline was controlled by the colonial powers. The raw materials and goods from China became controlled by the colonial power, which were making enormous amount of wealth from it, while the Chinese people were suffering in poverty.