Evaluate the Radical Function at the Given Value of the Variable

Multiple Choice

Evaluate the radical function at the given value of the variable.
- $$g ( x ) = \sqrt { 3 x ^ { 2 } + 9 }$$

A) $[ - 3 , \infty )$
B) $( - 3 , \infty )$
C) $( - \infty , \infty )$
D) $[ 0 , \infty )$