Marginalism is the study of how much extra use is gained from incremental increases in the quantity of goods created, sold, or consumed.
Option: A
Step-by-step explanation:
Marginalism is an important theory of economics. It is the study of quality of products for judging its power to serve extra use by increasing its number incrementally. Marginalism prevails in that condition where quantity of products slightly increase in respect of creation, selling and consumption.
Marginalism does not exist in the situation of no surplus or no shortage means in equilibrium condition. A good's capacity of giving extra service on extra use is called marginal service capacity or marginal productivity. For reaching the satisfaction level of buyers extra use of increased quantity of good is required.