If $$n$$ is the number density and $$d$$ is the diameter of the molecule, then the average distance covered by a molecule between two successive collisions (i.e. mean free path) is represented by :

A

$$\sqrt{2} n\pi d^2$$

B

$$\frac{1}{\sqrt{2n\pi d^2}}$$

C

$$\frac{1}{\sqrt{2} n\pi d^2}$$

D

$$\frac{1}{\sqrt{2} n^2 \pi^2 d^2}$$