The correlation between stocks A and B is equal to the:
standard deviation of A divided by the standard deviation of B.
covariance of A and B divided by the product of the standard deviation of A multiplied by the standard deviation of B.
standard deviation of B divided by the covariance between A and B.
sum of the variances of A and B divided by the covariance of A and B.
product of the standard deviation of A multiplied by the standard deviation of B divided by covariance of AB with the market.