If $$4 \cos^2 \theta - 3 \sin^2 \theta + 2 =0,$$ then the value of $$\tan \theta$$ is (where $$0 \leq \theta < 90^\circ$$)

A

1

B

$$\sqrt 6$$

C

$$\sqrt 2$$

D

$$\frac {1}{\sqrt 3}$$