已知 $f(x)=\left\{\begin{array}{cc}\left|4-x^2\right|, & x \leqslant 0, \\ \frac{1}{x}, & x>0\end{array}\right.$, 若 $x_1 < x_2 < x_3$ 满足 $f\left(x_1\right)=f\left(x_2\right)=f\left(x_3\right)$, 则 $\frac{x_1 x_2}{x_3}$ 的取值范围为
A. $(0,2 \sqrt{3}]$
B. $(0, \sqrt{15}]$
C. $(0,8]$
D. $(0,64]$