A market economy is regulated by the interactions between which two things

producers and consumers

Explanation:

Market economy is understood as an economic system marked by the predominance of private initiative in the economy. In this model, the existence of public or state-owned companies in the economy is admitted, but these should be fewer and should not dictate the pace of trade. This type of economy is regulated by the interactions between producers and consumers in an extensive process of buying and selling.

This economic model was accompanied, first, by economic liberalism, which advocated the minimal intervention of the State in the economy. Later, after the 1970s, this model was resumed in association with neoliberalism, which again preached the minimal intervention of the State in the economy, except in times of crisis and social and economic instability. Currently, virtually all countries in the world adopt this model.

I just took both AP micro and macro. I don't think any answer would be more appropriate than suppliers and demanders.