A firm uses backflush costing to assign product costs to inventory. The firm values inventory using throughput accounting. At the beginning of February, the RIP account has a balance of $450. On February 10, the firm purchased 2,000 lbs of raw materials worth $20,000. At the end of the month, 30 lbs of raw materials (worth $300) remain unused. 100 units were in process ($10 material cost per unit) If you searched for the RIP account in the firm's cost accounting records on February 15, what balance would that account show? a. $750 b. $20,000 c. $450