A portfolio is comprised of equal weights of two stocks labeled Stock X and Stock Y. The covariance between Stock X and Stock Y is 0.10. The standard deviation of Stock X is 0.50, and the standard deviation of Stock Y is 0.50. Which of the following comes closest to the variance of the portfolio?
a. 0.18
b. 0.60
c. 0.55
d. 1.00
e. 0.42