In a capitalist economy, the answer to the fundamental questions of what, how, and for whom to produce, are obtained by:
Market forces are the factor that authority the price and accessibility of goods and services in a market economy i.e. an economy with the minimum of government involvement. Market services move forwards prices up when supply decline and demand rise and make them down when supply grow or demand contract.
Market forces of demand and supply representing the collective authority of self interested buyers and seller on price and quantity of the good and services obtainable in a market. In general, surplus demand causes prices and quantity of supply to rise and excess supply cause them to fall.
The correct option is A.