Evaluate the Radical Function at the Given Value of the Variable

Multiple Choice

Evaluate the radical function at the given value of the variable.
- $$f ( x ) = \sqrt { 4 x + 9 }$$

A) $\left( \frac { 9 } { 4 } , \infty \right)$
B) $\left( - \frac { 9 } { 4 } , \infty \right)$
C) $\left[ - \frac { 9 } { 4 } , \infty \right]$
D) $\left( - \infty , - \frac { 9 } { 4 } \right)$