You own a portfolio that has 35% invested in asset A, and 65% invested in asset B. Asset As standard deviation is 12% and asset Bs standard deviation is 18%. The correlation coefficient between the two assets is -0.7. The expected return on the portfolio is 13%. What is the portfolio standard deviation? a.) 8.5% b.) 9.3% c.) 7.2% d.) 15.3%