If $$\sqrt{\frac{1 - \cos \theta}{1 + \cos \theta}}\times\sqrt{\frac{\cosec \theta - \cot \theta}{\cosec \theta + \cot \theta}} = \frac{1 - r}{1 + r}$$, then the value of r is:

A

$$\cos \theta$$

B

$$\cosec \theta$$

C

$$\sin  \theta$$

D

$$\sec \theta$$