Compared to Taxing Pollution, an Advantage of Auctioning Pollution Permits

Compared to taxing pollution, an advantage of auctioning pollution permits is that:

A) the largest reductions in pollution are made by the firms that can do so the most cheaply.
B) auctioning permits raises revenue for the government.
C) it allows the public to directly reduce pollution by purchasing permits.
D) it ensures that all firms reduce pollution by the same amount.