The correct answer is C) contrast.
The connection between the ideas in these sentences is "contrast."
When we use contrast, we want t to compare two sentences, two assumptions, or two facts, so we can see the similarities or the differences and could get to a conclusion. This is done to have a much better perspective of the object of study. In this case, if many people believe a European named Johannes Gutenberg invented the printing press, we have to take into consideration that Gutenberg’s press was actually building on inventions that appeared centuries earlier in China. So Gutenberg based his work on previous works from Chinese people.
With this contrast, we are able to understand that the Chinese have their own merit in this marvelous discovery.