The United States has a mixed economy.
The United States sets a federal minimum wage (States are able to either abide or raise upwards of the federal minimum wage). Most of the economical powers are left towards state and local governments, who understand what the community needs. The federal government simply sets regulations on foreign trades, state trades, and provide federal funding to different fields (of work) when needed.
A is correct.
The US government had a very hands off approach from the creation of the nation up to the Great Depression. At first, the US government did not even obtain taxes to help run the government, for fear that the US people would rebel. (Remember, the US broke away from the British Empire simply because of excessive taxes, and if the US government was to quickly impose it's own taxes, it feared being toppled).
However, with uncontrolled growth and no security, the market crashes during the Great Depression saw to the US government playing a larger role in the public economy, to help secure the upwards trend of the economy and to be able to inject or remove cash from the market cycle to help keep the economy afloat.