Two Firms, Acme and FirmCo, Have Access to Five Production

Multiple Choice

Two firms, Acme and FirmCo, have access to five production processes, each of which has a different cost and gives off a different amount of pollution. The daily costs of the processes and the corresponding number of tons of smoke emitted are shown in the table below.  
Suppose the firms are both currently using process A. If the government imposes a tax of $110 per ton of smoke emitted, then Acme will use process ________, and FirmCo will use process ________.

A) B; A
B) C; A
C) C; C
D) D; C