Help me please!!
  Worker hours to produce one barrel of crude oil Worker hours to produce one ton of coal

United States
Developed
4
5

Country A
Developing
6
5

Country B
Developed
7
3

Using the chart, identify an example of comparative advantage for the United States over either Country A or Country B. Be sure to identify the product and the country. Explain how the availability and use of a natural resource may impact advantage.