问题
以下关于无穷限的反常积分 $\textcolor{Orange}{\int_{- \infty}^{b}}$ $\textcolor{Orange}{f(x)}$ $\textcolor{Orange}{\mathrm{d} x}$ 的结论中，正确的是哪个？选项
[A]. $\int_{- \infty}^{b}$ $f(x)$ $\mathrm{d} x$ $=$ $\lim_{a \rightarrow + \infty}$ $\int_{a}^{b}$ $f(x)$ $\mathrel{d} x$[B]. $\int_{- \infty}^{b}$ $f(x)$ $\mathrm{d} x$ $=$ $\lim_{a \rightarrow – \infty}$ $\int_{a}^{b}$ $f(x)$ $\mathrel{d} x$
[C]. $\int_{- \infty}^{b}$ $f(x)$ $\mathrm{d} x$ $=$ $\lim_{b \rightarrow – \infty}$ $\int_{a}^{b}$ $f(x)$ $\mathrel{d} x$
[D]. $\int_{- \infty}^{b}$ $f(x)$ $\mathrm{d} x$ $=$ $\lim_{a \rightarrow – \infty}$ $\int_{b}^{a}$ $f(x)$ $\mathrel{d} x$
$$\int_{\textcolor{Red}{- \infty}}^{\textcolor{Red}{b}} f(x) \mathrm{d} x =$$ $$\lim_{\textcolor{Orange}{a} \textcolor{Green}{\rightarrow} \textcolor{Orange}{- \infty}} \int_{\textcolor{Red}{a}}^{\textcolor{Red}{b}} f(x) \mathrel{d} x$$