Kim Airedale, a manager of Waggers, Inc., was reviewing the water bills of a dog daycare and spa. She determined that its highest and lowest bills of $3,200 and $2,000 were incurred in the months of May and November, respectively. If 400 dogs were washed in May and 200 dogs were washed in November , what was the variable cost per dog associated with the company's water bill? (Round your answer to the nearest cent.)

A. $8.00

B. $10.00

C. $6.00

D.$3.33