If $$\tan A + \sec A = K$$, then what is the value of $$\sin A$$?

A

$$\frac{2K}{K^2 + 1}$$

B

$$\frac{K^2 - 1}{2K}$$

C

$$\frac{K^2 + 1}{K^2 - 1}$$

D

$$\frac{K^2 - 1}{K^2 + 1}$$