The Timberline Firm Expects a Total Cash Need of $12,500

The Timberline firm expects a total cash need of $12,500 over the next 3 months. They have a beginning cash balance of $1,500, and cash is replenished when it hits zero. The fixed cost of selling securities to replenish cash balances is $3.50. The interest rate on marketable securities is 8% per annum. There is a constant rate of cash disbursement and no cash receipts during the month.
-What is the firm's disbursement float?

A) $-10,500
B) $-8,700
C) $1,800
D) $10,500
E) None of the above.