Producer surplus is most accurately defined as the.（）
选项：

A:difference between the opportunity cost of producing the last unit of a good or service and the price received for that unit.
B:sum of the differences between the marginal benefit and the marginal cost for each unit of good produced and consumed over the total number of units produced and consumed.
C:sum of the differences between the price received for each unit of good produced and the opportunity cost of each unit.