The Diagram Below Shows the Marginal Cost of Abatement for Each

The diagram below shows the marginal cost of abatement for each of two firms,A and B.Each firm is initially abating Q0 units of pollution.
FIGURE 17- 6
-Refer to Figure 17- 6.Suppose that a system of tradable pollution permits is introduced into this market and the equilibrium permit price is p*.Firm B will buy permits from Firm A because

A) Firm B has lower costs of pollution abatement than Firm A.
B) its total savings from abating less (areas 1+2+3) exceed the cost of buying the permits (areas 2+3) .
C) Firm B can buy the permits at a lower price than Firm A.
D) its total cost of abating less (areas 1+2+3) exceeds the cost of buying the permits (areas 2+3) .
E) its total savings from abating less (areas 1+2+3) exceed the total costs of Firm A abating more (area 6) .