1. If $-\frac{1}{2} \leqslant x \leqslant 1$, then
$$
\begin{array}{l}
\sqrt{x^{2}-2 x+1}+\sqrt{x^{2}-6 x+9}+\sqrt{4 x^{2}+4 x+1} \\
=(\quad) .
\end{array}
$$
(A) $-4 x+3$
(B) 5
(C) $2 x+3$
(D) $4 x+3$
$\begin{array}{l}\text { i.1. B. } \\ \text { Original expression }=|x-1|+|x-3|+|2 x+1| \\ =1-x+3-x+2 x+1=5 .\end{array}$