If $$x = X - \overline{X}$$ and $$y = Y - \overline{Y}$$ and the number of pairs $$(X,Y)$$ is n, then the Karl Pearson’s coefficient of correlation is:

A

$$\frac{n \sum xy}{\sqrt{\sum x^2 \sum y^2}}$$

B

$$\frac{\sum xy}{(\sum x^2 \sum y^2)^{\frac{1}{n}}}$$

C

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

D

$$\frac{\sum xy}{n \sum x^2 \sum y^2}$$