Which of the Following Is a Fourth Root Of $1 ?$

Which of the following is a fourth root of $1 ?$
I. $\cos \left( \frac { 3 \pi } { 2 } \right) + i \sin \left( \frac { 3 \pi } { 2 } \right)$
II. $\frac { 1 } { 4 } ( \cos ( 0 ) + i \sin ( 0 ) )$
III. $\cos \left( \frac { \pi } { 4 } \right) + i \sin \left( \frac { \pi } { 4 } \right)$

A) None are roots.
B) II and III are the only roots.
C) I and II are the only roots.
D) I, II, and III are roots.
E) I is the only root.