Write the Following as an Algebraic Expression in U, U $\tan \left(\cos ^{-1} \frac{\mathrm{u}}{3}\right)$

Write the following as an algebraic expression in u, u > 0.
- $\tan \left(\cos ^{-1} \frac{\mathrm{u}}{3}\right)$

A) $\frac{\sqrt{u^{2}-9}}{u}$

B) $\frac { u \sqrt { 9 - u ^ { 2 } } } { 9 - u ^ { 2 } }$

C) $u ^ { 2 } \sqrt { 9 }$

D) $\frac { \sqrt { 9 - u ^ { 2 } } } { u }$