Suppose There Are Three Power-Generating Plants, Each of Which Has

Multiple Choice

Suppose there are three power-generating plants, each of which has access to 5 different production processes. The table below summarizes the cost of each production process and the corresponding number of tons of smoke emitted each.  
Suppose the government imposes a tax of $21 on each ton of smoke emitted. To minimize costs, Firm X will emit ________ tons; Firm Y will emit ________ tons, and Firm Z will emit ________ tons.

A) 1; 2; 3
B) 2; 3; 4
C) 3; 4; 4
D) 1; 2; 4