The ratio of the covariance between x and y written as cov (x, y) to the product of the standard deviation of x and y symbolically

A. $$\frac{{\sum {\text{xy}}}}{{\sqrt {\sum {{\text{x}}^2} \cdot \sum {{\text{y}}^2}} }}$$

B. $${\text{r}} = \frac{{\operatorname{cov} \left( {{\text{x}},{\text{y}}} \right)}}{{\sigma {\text{x}},\,\sigma {\text{y}}}}$$

C. $$\frac{{\sqrt \sum {{\text{x}}^2}\sum {{\text{y}}^2}}}{{\sum {\text{xy}}}}$$

D. None of these

Answer: Option B