Answer :
The US is described as a mixed market economy because both the government and the private sector take a role in economic planning. The government doesn't completely control the economy thus it is shared with the private sector and called a mixed market economy.
The correct answer is: "because the goverment and other economic authorities intervene in market mechanisms"
The US economy is a mixed market economy because the interactions of economic agents (households, firms and public entities) determine market outcomes: prices and amounts exchanged of the different products and services.
But these outcomes are influenced by government interventions, aiming to reach fairer ones that benefit all the agents that participate in the economy, when resources had been allocated unequally by the market mechanism alone.
