Convert from Rectangular to Trigonometric Form $\theta$ Such That $0 \leq \theta < 2 \pi$

Multiple Choice

Convert from rectangular to trigonometric form. (Choose an argument $\theta$ such that $0 \leq \theta < 2 \pi$ .) 6

A) $6 ( \cos \pi + i \sin \pi )$
B) $6 ( \sin 0 )$
C) $6 ( \sin \pi + i \cos \pi )$
D) $6 ( \cos 0 + i \sin 0 )$
E) $6 ( \sin 0 + i \cos 0 )$