If 1 0^x = 1/2 then 1 0^ - 8x = ?

Answer: Option D

$$\begin{array}{rl}& \text{1}{\text{0}}^{-8x}\\ & ={\left[{10}^x\right]}^{-8}\\ & ={\left[\frac{1}{2}\right]}^{-8}\\ & =2^8\\ & =256\end{array}$$