If _2 [ _3 ( _2x ) ] = 1, then x is equal to = ?

Answer: Option D

$$\begin{array}{rl}& {\log }_2\left[{\log }_3\left({\log }_{2}x\right)\right]=1\\ & \Rightarrow {\log }_3\left({\log }_{2}x\right)=2^1=2\\ & \Rightarrow {\log }_{2}x=3^2=9\\ & \Rightarrow x=2^9=512\end{array}$$