12. An investment has a 10% probability of earning a 20% rate of return, a 60% probability of earning a 10% rate of return and a 30% probability of losing 5%. What is the standard deviation of the rate of return for this investment? _____.

A) 0.05 (5%)

B) 0.06 (6%)

C) 0.07 (7%)

D) 0.08 (8%)

E) 0.09 (9%)