20
Lesson 20 of 84 · Trade and Commerce
How Ports and Harbors Work
Prices are determined by supply and demand. When many people want the same scarce product, prices rise. Competition among sellers can bring prices down.
Key Facts
1
Trade connects people globally.
2
Every choice has an opportunity cost.
3
Money is a medium of exchange.
Check Your Understanding
Question 1
1 of 2What is an opportunity cost?