You are investing for your retirement. You put 50% of your money into stock A, with an expected return of 10%, and a standard deviation of 20%. The rest is invested in stock B, with an expected return of 20%, and a standard deviation of 30%. The correlation coefficient between Stock A and Stock B is 0.2. What is the standard deviation of your retirement portfolio? O 19.6% O 3.85% O 25% not enough information