On an average day, Tennis R Us writes checks totaling $2,000. These checks take 3 days to clear. The company receives checks totaling $1,800. These checks take 2 days to clear. The cost of debt is 8%. What is the firm's collection float? A. $-4,500 B. $-3,600 C. $3,600 D. $4,500 E. None of these.