The product moment correlation coefficient is obtained by the formula

A. $${\text{r}} = \frac{{\sum {\text{xy}}}}{{{\text{N}}\sigma {{\text{x}}^2}}}$$

B. $${\text{r}} = \frac{{\sum {\text{xy}}}}{{{\text{xy}}}}$$

C. $${\text{r}} = \frac{{\sum {\text{xy}}}}{{{\text{N}}\sigma {\text{x}}\,\sigma {{\text{y}}^2}}}$$

D. $${\text{r}} = \frac{{\sum {\text{x}}\,\sum {\text{y}}}}{{\sigma {\text{x}}\,\sigma {{\text{y}}^2}}}$$

Answer: Option C