Find the point(s) of intersection of the curves $r = 9$ and $r = 18 \sin \theta$.
A. $(9, \frac{\pi}{3}), (9, \frac{2\pi}{3})$
B. $(9, \frac{\pi}{4}), (9, \frac{3\pi}{4})$
C. $(9, \frac{\pi}{6}), (9, \frac{5\pi}{6})$
D. $(9, \frac{\pi}{6})$
E. $(9, \frac{\pi}{3})$