Use an Inverse Function to Write $\theta$ As a Function of X

Multiple Choice

Use an inverse function to write $\theta$ as a function of x.

A) $\theta = \arctan \frac { \sqrt { x ^ { 2 } - 9 } } { 3 }$
B) $\theta = \arctan \frac { 3 } { x }$
C) $\theta = \arctan \frac { 3 \pi } { x }$
D) $\theta = \arctan \frac { \sqrt { x ^ { 2 } + 9 } } { 3 }$
E) $\theta = \arctan \frac { x } { 3 }$