Explain the following paragraph.

"A nation which has can produce at a lower cost when measured in terms of opportunity cost is said to have a comparative advantage. Even though the U. S. has an absolute advantage in needing fewer workers to produce a given quantity of either shoes or refrigerators.

Mexico has a comparative advantage in production of shoes and the U. S. has a comparative advantage in the production of refrigerators.

Comparative advantage identifies the area where a producer's absolute advantage is relatively greatest, or where the producer's absolute disadvantage in productivity is relatively least. The U.S. can produce 1,000 shoes with four-fifths as many workers as Mexico ( 4 vs. 5), but can produce 1,000 refrigerators with only one-quarter as many workers (1 vs. 4).

Thus, the comparative advantage of the U. S., where its absolute productivity advantage is relatively greatest, lies with refrigerators, and Mexico's comparative advantage, where its absolute productivity disadvantage is least, is in the production of shoes."