If $\tan A = \frac{1}{2}$ and $\tan B = \frac{1}{3}$, then $A+B$ is equal to :

Question

( A ) $\frac{\pi}{3}$
( B ) $\frac{\pi}{2}$
( C ) $\frac{\pi}{6}$
( D ) $\frac{\pi}{4}$