Answer: Opportunity cost
Step-by-step explanation:
Mixed economy is an economic system which has to do with all the economic agents involved in the production and distribution of the goods and the services produced in an economy.
Opportunity cost is what we give up when we make a choice. Due to scarcity of resources, we make choices and we have to forgo some in order to have something else.
Factors of production are the resources that are used for productive purpose like land, labor, capital and the enterprise.
Capital has to do with the technology used for production.
Therefore, the answer is opportunity cost.