Use the Trigonometric Substitution to Rewrite the Algebraic Expression as a Trigonometric

Use the trigonometric substitution to rewrite the algebraic expression as a trigonometric function of $\theta$ , where $- \frac { \pi } { 2 } < \theta < \frac { \pi } { 2 }$ .Then find sin $\theta$ and cos $\theta$ .
$3 \sqrt { 3 } = \sqrt { 81 - 9 x ^ { 2 } } , x = 3 \cos \theta$

A) $\sin \theta = 3 ; \sin \theta = \frac { \sqrt { 3 } } { 3 } ; \cos \theta = \frac { \sqrt { 6 } } { 3 }$
B) $3 \sin \theta = 3 ; \sin \theta = 0 ; \cos \theta = 1$
C) $\sin \theta = \sqrt { 3 } ; \sin \theta = \frac { \sqrt { 3 } } { 3 } ; \cos \theta = \frac { \sqrt { 6 } } { 3 }$
D) $9 \sin \theta = 3 \sqrt { 3 } ; \sin \theta = \frac { \sqrt { 3 } } { 3 } ; \cos \theta = \frac { \sqrt { 6 } } { 3 }$
E) $3 \cos \theta = 3 ; \sin \theta = 1 ; \cos \theta = 0$