Answer:
A) taking the cost into account because money spent on pollution reduction is not available for other worthy activities.
Step-by-step explanation:
The economic approach tries to find solutions for problems optimizing the use of economic resources, therefore reducing costs and increasing benefits for every dollar spent.
Resources are scarce and that includes everyone, from a normal individual, to the richest person in the world, or the richest country in the world. The economic approach states that we should all try to maximize the benefits we obtain while exchanging resources. For example, if we need to study for a text and we know that solving problems helps us to learn more than just reading, then we should spend more time solving problems than reading because that way we can increase our benefits.
The US government and every other government in the world works on a budget and the money it spends doing A, will not be spent doing B. So the government must decide which actions to take in order for maximizing the benefits of the population (i.e. choose between A or B depending on which causes the greatest common good).