Determine All Critical Points for the Function $$f ( x ) = x ^ { 2 } + 6 x + 9$$

Multiple Choice

Determine all critical points for the function.
- $$f ( x ) = x ^ { 2 } + 6 x + 9$$

A) $x = 3$
B) $x = - 3$
C) $x = 0$
D) $x = - 6$