Economists say that individuals make decisions at the margin. What does its menas?

When Economists say that humans make decisions at the margin they mean that decisions are made on the basis of the cost and benefit of getting an additional unit of a good/ service.

Marginal benefit refers to the additional utility that we will derive from consuming one extra unit of a good or service and factors in heavily into our decision making. We usually accept a decision if the Marginal benefit is higher or equal to the Marginal cost ( cost of the additional unit) of the good/service.

If the Marginal Cost is instead higher, the decision would most probably be cancelled.

a.

answer; schedule c;