Answer:
d. Private sector through the earning and spending of income.
Explanation:
In economics some major questions producers ask is for whom is production done, and how are output distributed in the economy.
For example ski equipment are produced for those people that practice skiing either as a sport or as a hobby. The particular set of people that use this product is targeted and provided with these goods.
Therefore these questions are answered in the private sector when the consumer earns income and spends it on their needs.