You have an equally weighted portfolio containing shares in Company A and Company B. The standard deviation of the returns on Company A shares is 11% and the standard deviation for Company B shares is 9%. The two shares' returns have a covariance of 0.0012423. What is the standard deviation or risk of your portfolio?

a. 0.00567115

b. 8.23%

c. 0.0023256

d. 17.80%

e. 7.53%