TSBT would like to maintain their cash account at a minimum level of $45,000, but expect the standard deviation in net daily cash flows to be $5,000; the effective annual rate on marketable securities to be 4.5 percent per year, and the trading cost per sale or purchase of marketable securities to be $50 per transaction. What will be their optimal cash return point?

A. $44,809.47 B. $ 64,809.47 C. $73,431.54