The interval $(s)$ of decrease of the function $f(x)=$ $x^{2} \log 27-6 x \log 27+\left(3 x^{2}-18 x+24\right) \log \left(x^{2}-6 x\right.$
$+8)$ is
(a) $(3-\sqrt{1+13 e}, 2)$
(b) $(4,3+\sqrt{1+1 / 3 e})$
(c) $(3,4+\sqrt{1+1 / 3 e})$
(d) none of these