Final answer:
A teenage girl deciding how to spend her money earned from working overtime is an example of a participant in a market economy, as this reflects personal choice and market principles.
Step-by-step explanation:
In a market economy, individuals and businesses make most economic decisions, including what is to be produced, how to produce goods and services, and for whom they are to be produced. The participants in a market economy perform these activities based on supply and demand, and through the price system. The choices they make are influenced by the incentives to earn profits and the necessity to satisfy consumer demands.
Looking at the provided options, the most likely participants in a market economy would be those making decisions influenced by market forces, rather than by government directives. Therefore, among the options provided, a teenage girl deciding how to spend the money she earned working overtime is the best example of a participant in a market economy. This decision reflects personal choice and the freedom to decide how to utilize earnings, aligning closely with the principles of a market economy where individuals make decisions based on their own self-interest.