Using the rational numbers $\frac{1}{3}, \frac{1}{6}, \frac{6}{8}, \frac{8}{12}, \frac{9}{36}$, two groups with two elements each are formed such that the sum of the numbers in the same group equals 1.
According to this, which of these numbers is not included in the formed groups?
A) $\frac{1}{6}$
B) $\frac{1}{3}$
C) $\frac{6}{8}$
D) $\frac{8}{12}$
E) $\frac{9}{36}$