Agents of Production

There are Four agents of  Production:
-Land
-Labour
-Capital 
-Entrepreneurship

Last year a farmer's crop yielded $100 worth of produce.

To generate that selling price, the farmer incurred $25 to rent the land, $25 to pay for labor, and $25 for the use of equipment. The remaining $25 compensates him for his effort as an entrepreneur.

Source: http://www.allbusiness.com/