3 0.000064 = ?

Answer: Option B

$$\begin{array}{rl}& =\sqrt{0.000064}\\ & =\sqrt{\frac{64}{{10}^6}}\\ & =\frac{8}{{10}^3}\\ & =\frac{8}{1000}\\ & =0.008\\ & \therefore \text{root}3\text{of}\sqrt{0.000064}\\ & =\text{root}3\text{of}0.008\\ & =\text{root}3\text{of}\frac{8}{1000}\\ & =\frac{2}{10}\\ & =0.2\end{array}$$