1. Simplify the radical expression $\frac{\sqrt{2}(\sqrt{6}-\sqrt{3}-\sqrt{2}+1)}{\sqrt{3-2 \sqrt{2}} \cdot \sqrt{2-\sqrt{3}}}$, the result is ( ).
(A) 2
(B) -2
(C) $\sqrt{2}$
(D) $-\sqrt{2}$
$\begin{array}{l}\text { I. 1. A. } \\ \text { Original expression }=\frac{\sqrt{2}(\sqrt{2}-1)(\sqrt{3}-1)}{\sqrt{(1-\sqrt{2})^{2}} \cdot \sqrt{\frac{4-2 \sqrt{3}}{2}}} \\ =\frac{2(\sqrt{2}-1)(\sqrt{3}-1)}{\sqrt{(1-\sqrt{2})^{2}} \cdot \sqrt{(1-\sqrt{3})^{2}}}=2 .\end{array}$