Keep control of the highly valuable trade item.
Porcelain was a highly valuable item traded out of China. Keeping the process of creating porcelain secret meant China could maintain control over the product. This made porcelain highly valuable and a luxury item that the Chinese could market for high prices. Porcelain items were in demand from wealthy people around the world and they could only get those items from the Chinese who held the process secret. In exchange, the Chinese could demand a high price or valuable items from other places in the world.
Explanation:
Ceramic objects are often identified by their marks. Marks like the Chelsea anchor or the crossed-swords of Meissen are well known (and were often pirated), while the significance of others is uncertain.
I think it's b. I took the test and a. was wrong