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. 0.55

b. 0.18

c. 1.00

d. 0.42

e. 0.60