Chọn phương án D.

\(\begin{aligned}\lim\limits_{x\to-\infty}\left(x-x^3+1\right)&=\lim\limits_{x\to-\infty}x^3\left(\dfrac{1}{x^2}-1+\dfrac{1}{x^3}\right)\\
&=+\infty.\end{aligned}\)

Vì \(\begin{cases}
\lim\limits_{x\to-\infty}x^3&=-\infty\\
\lim\limits_{x\to-\infty}\left(\dfrac{1}{x^2}-1+\dfrac{1}{x^3}\right)&=-1<0.
\end{cases}\)