The simplest value of
$$\frac{1}{\sqrt{2} + \sqrt{3}} + \frac{1}{\sqrt{3} + \sqrt{4}} + \frac{1}{\sqrt{4} + \sqrt{5}} + \frac{1}{\sqrt{5} + \sqrt{6}}$$

A

$$\sqrt{3}(\sqrt{2} - 1)$$

B

$$\sqrt{2}(\sqrt{3} - 1)$$

C

$$\sqrt{3} - 1$$

D

$$\sqrt{2} -1$$