14. The beta of a security is equal to (4 points) A. the covariance between the security and market returns divided by the standard deviation of the market's returns B. the variance of the security's retums divided by the covariance between the security and market returns C. the covariance between the security and market returns divided by the variance of the market's returns D. the variance of the security's retums divided by the variance of the market's returns