NAFTA was important to North American countries because it . A. broke down trade barriers B. established a military alliance C. promoted alternative energy sources D. provided free healthcare for all people

Option A (broke down trade barriers) is the appropriate choice.

Explanation:

NAFTA seems to have been a contentious trading relationship agreed to sign which progressively removed that very many tariff barriers to exchange throughout commodities having to pass only between the U.S and other two regions. The agreement succeeded in creating a coalition of international markets between the third biggest regions such as North America.

The other alternatives aren't related to the type of situation in question. Therefore this response seems to be the correct one.