The beta of a stock is a measure of the sensitivity of its returns to those of the market as a whole. When linear regression is used to compare the returns of a stock market index to those of a particular investment, the best way to express beta is:

a. The covariance of the assets returns with those of the market, divided by the variance of the markets returns

b. The correlation coefficient between the returns of the market and those of the asset, times the standard deviation of the assets returns, divided by the standard deviation of the markets returns

c. Both of these answers are correct