Answer:
The idea of the margin is related to making decisions while thinking about the benefits and costs of small changes in behavior.
Explanation:
Economic theory suggests that economic agents (firms, consumers and government) think on the sidelines. This means that decisions are made taking into consideration the benefits and costs of each choice. For example, for a firm to increase a unit of production (marginal unit) it will calculate the cost of production of that unit (marginal cost) and the profit that additional unit will generate (marginal benefit).