If $$\sin \theta = \frac{a}{\sqrt{a^2 + b^2}}, 0^\circ < \theta < 90^\circ$$, then the value of $$\sec \theta + \tan \theta$$

A

$$\frac{\sqrt{a^2 + b^2} + a}{b}$$

B

$$\frac{\sqrt{a^2 + b^2} + b}{2a}$$

C

$$\frac{\sqrt{a^2 + b^2} + a}{2b}$$

D

$$\frac{\sqrt{a^2 + b^2} + b}{a}$$