The value of 2 10 5 + 2 - 7 - 5 - 2 5 + 2 - 3 7 - 2 is:

Answer: Option C

$$\begin{array}{rl}& \frac{2\sqrt{10}}{\sqrt{5}+\sqrt{2}-\sqrt{7}}-\sqrt{\frac{\sqrt{5}-2}{\sqrt{5}+2}}-\frac{3}{\sqrt{7}-2}\\ & =\frac{2\sqrt{10}\left(\sqrt{5}+\sqrt{2}+\sqrt{7}\right)}{{\left(\sqrt{5}+\sqrt{2}\right)}^2-{\left(\sqrt{7}\right)}^2}-\sqrt{\frac{{\left(\sqrt{5}-2\right)}^2}{{\left(\sqrt{5}\right)}^2-{\left(2\right)}^2}}-\frac{3\left(\sqrt{7}+2\right)}{{\left(\sqrt{7}\right)}^2-{\left(2\right)}^2}\\ & =\frac{2\sqrt{10}\left(\sqrt{5}+\sqrt{2}+\sqrt{7}\right)}{5+2+2\sqrt{10}-7}-\frac{\left(\sqrt{5}-2\right)}{1}-\frac{3\left(\sqrt{7}+2\right)}{3}\\ & =\sqrt{5}+\sqrt{2}+\sqrt{7}-\sqrt{5}+2-\sqrt{7}-2\\ & =\sqrt{2}\end{array}$$