B

- Hướng dẫn giải

Đáp án B

Ta có: $F\text{'}\left(x\right)=\left(3a{x}^2+2bx+c\right)e^{-x}$$-e^{-x}\left(a{x}^3+b{x}^2+cx+d\right)$

$=e^{-x}\left[-a{x}^3+\left(3a-b\right)x^2+\left(2b-c\right)x+c-d\right]$

$\begin{array}{l}F\text{'}\left(x\right)=f\left(x\right)\forall x\\ \iff \left\{\begin{array}{l}-a=-2\\ 3a-b=3\\ 2b-c=7\\ c-d=-2\end{array}\right.\\ \iff \left\{\begin{array}{l}a=2\\ b=3\\ c=-1\\ d=1\end{array}\right.\\ \Rightarrow a+b+c+d=5\end{array}$