In a mixed-market economy, the government regulates business

Only when necessary is the right answer.

A mixed economy system is a system in which the elements of capitalism and socialism are observed. This system protects private investments and provides a level of economic freedom in the use of resources, but in order to achieve its social goal,ls it also allows the government to interfere in economic activities.  

The government regulates business, for several reasons such as for public safety and welfare, protection of industry, and also for revenue generation. However, government can only interfere in the economic activities only when it became a necessity.  

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