The correct answer is B) "Bought grain, stored it, and resold it during times of low harvest":
Following a tendency of nationalizing several industries, which included salt, iron, and liquor, emperor Wu decided to interfere with the trade of grain in 110 BC. This happened as a response from the government to eliminate speculation generated by merchants by selling previously stored grain at below-market prices.
A. coffee beans
All the others were introduced as a result of The Colombian exchange
