Two Firms,A and B,are Legally Required to Reduce Their Toxic

Two firms,A and B,are legally required to reduce their toxic emissions.If Firm A's marginal cost of abatement is $5 and Firm B's marginal cost of abatement is $5,

A) their joint total cost of abatement is at a minimum.
B) their joint total cost of abatement is at a maximum.
C) the socially optimal joint level of abatement is not being achieved.
D) Firm A should abate more and Firm B should abate less.
E) Firm B should abate more and Firm A should abate less.