Answer:
Among the earliest inventions were the abacus, the sundial, and the Kongming lantern. The Four Great Inventions,the compass, gunpowder, papermaking, and printing – were among the most important technological advances, only known to Europe by the end of the Middle Ages 1000 years later.
Explanation:
I believe the answer would be opportunity cost. the opportunity cost is the cost to create an item which can result an increase in the price to ensure they make profit
Invading soldiers burned wheat crops