On an average day, a company writes checks totaling $1,500. These checks take 7 days to clear. The company receives checks totaling $1,800. These checks take 4 days to clear. The cost of debt is 9%. What is the firm's disbursement float? A. $-10,500 B. $-8,700 C. $1,800 D. $10,500 E. None of these.