A country would most likely adopt a market economy if it wanted to

Make sure prices of goods and services are set by supply and demand.

Explanation:

The economies of the United States and other countries, such as Japan, are based on capitalism ... Decisions regarding investment and the use of the means of production are determined by competing business owners in the marketplace. Production takes place within the process of capital accumulation.

Countries that have a market economy are Mexico, United States, United Kingdom, Germany, and Canada. These countries have a market economy because the prices of goods and services are set by supply and demand.