You sell short 300 shares of Microsoft which are currently selling at $30 for each share. You post the 50% margin required on the short sale. If you earn no interest on funds in your margin account, what will be your rate of return after 1 year if Microsoft is selling at $27? (Ignore any dividends.)
A. 6.67%
B. 15%
C. 10%
D. 20%