Given $f(x)=x^{2}+4 x+15$ Find All Values For $x$ For Which $f(x) \leq 3$

Multiple Choice

Given $f(x) =x^{2}+4 x+15$ find all values for $x$ for which $f(x) \leq 3$ .

A) $(-\infty,-6] \cup[2, \infty)$
B) $(-6,2)$
C) $[-6,2]$
D) $\varnothing$