I think it's b. I took the test and a. was wrong
B. Artisans
Good luck in the rest of the test my friend! :)
The answer is B. to profit from the fur trade.
In an explanatory essay, or any essay, the introductory paragraph introduces (hence it's name) the main idea, or what you are going to explain. The body paragraphs go into extreme detail of what the introductory paragraphs mentioned.