The correct answer is B) Mixed economy.
A mixed economy is one that has elements of government involvement in the economy and the freedom of businesses to make decisions on their own. In the US, the government is involved in the econommy by ensuring that monopolies aren't formed, that businesses are following certain health and safety standards in the work place, etc. However, the government does not have the right to tell businesses what to make. Businesses decide who they hire, how many products they will generate, and what they will charge for their goods/services.