Evaluate $$\int_{0}^{1} \int_{0}^{1} \frac{1}{\sqrt{(1 - x^2)(1 - y^2)}} dxdy$$

A

$$\frac{\pi}{2}$$

B

$$\frac{\pi}{4}$$

C

$$\frac{\pi^2}{2}$$

D

$$\frac{\pi^2}{4}$$