The ""invisible hand"" refers to a. how central planners made economic decisions. b. how the decisions of households and firms lead to desirable market outcomes. c. the control that large firms have over the economy. d. government regulations without which the economy would be less efficient.

How the decision of household and firm leads to desirable market outcomes.  

Explanation:

Invisible hands were introduced first by Adam Smith in his book The Wealth of Nation. He assumed that economy work free in the market and everyone work there benefits and interest. The un-observable hand that provides help to support the supply of goods in the market to reach equilibrium automatically is called Invisible hands. He explained that economic work well if govt. leave the people to work freely among themselves. Again he, if people are allowed to trade freely in the market and self-interested traders present in the market, would compete with each other leading the market towards the positive development of the economy of a country. This process would help in the positive development of Invisible hands.

the answer is:

c. economic output