Answer the Question About the Given Function $$f ( x ) = - 6 x ^ { 2 } - 12 x + 5$$

Answer the question about the given function.
-Given the functi $$f ( x ) = - 6 x ^ { 2 } - 12 x + 5$$ , what is the domain of f?

A) all real numbers
B) {x|x ≥ -1}
C) {x|x ≥ 1}
D) {x|x ≤-1}