$\lim _{n \rightarrow \infty} \frac{\sqrt[n]{\left(n^2+1\right)\left(n^2+2\right) \cdot\left(n^2+n^2\right)}}{n^2}=()$
$\text{A.}$ $e^{\frac{\pi}{4}-1}$ ．
$\text{B.}$ $2 e ^{\frac{\pi}{4}-1}$ ．
$\text{C.}$ $e^{\frac{\pi}{2}-2}$ ．
$\text{D.}$ $2 e ^{\frac{\pi}{2}-2}$ ．
$\text{E.}$
$\text{F.}$