Find the Trigonometric Form of the Complex Number Shown Below $- 7 i$

Multiple Choice

Find the trigonometric form of the complex number shown below. $- 7 i$

A) $7 ( \cos 0 + i \sin 0 )$
B) $7 ( \cos \pi + i \sin \pi )$
C) $7 \left( \cos \frac { 3 \pi } { 2 } + i \sin \frac { 3 \pi } { 2 } \right)$
D) $7 \left( \cos \frac { \pi } { 4 } + i \sin \frac { \pi } { 4 } \right)$
E) $7 \left( \cos \frac { \pi } { 2 } + i \sin \frac { \pi } { 2 } \right)$