$$\alpha = \cos \frac { \pi } { 3 } + i \sin \frac { \pi } { 3 }$$
Given that, which of the following is $\alpha ^ { 23 }$ equal to?\\
A) $\cos \frac { \pi } { 6 } + i \sin \frac { \pi } { 6 }$\\
B) $\cos \frac { 2 \pi } { 3 } + i \sin \frac { 2 \pi } { 3 }$\\
C) $\cos \frac { 4 \pi } { 3 } + i \sin \frac { 4 \pi } { 3 }$\\
D) $\cos \frac { 5 \pi } { 3 } + i \sin \frac { 5 \pi } { 3 }$\\
E) $\cos \pi + \mathrm { i } \sin \pi$