When you say "which," it sounds like it should be multiple choice. Anyways, here's the simplified form of [tex]\sqrt{\frac{1}8}}[/tex]
[tex]\sqrt{\frac{1}8}} = \frac{\sqrt{1}}{\sqrt{8}} = \frac{1}{\sqrt{8}} * \frac{\sqrt{8}}{\sqrt{8}}=\boxed{\frac{\sqrt{8}}8}[/tex]
(When simplifying fractions, you should never have a square root on the bottom. Multiply by the square root to cancel it out)
