An investor invests 40% of his wealth in a risky asset with an expected rate of return of 10% and a standard deviation of 20%, and 60% in a treasury bill that pays 4%. How much is her complete portfolio's expected rate of return and standard deviation?

A) 7.6% and 12%

B) 6.4% and 8%

C) 6.4% and 20%

D) 7.2% and 20%