The least among the following is:

Answer: Option D

$$\begin{array}{rl}& 1÷0.2=\frac{1}{0.2}=\frac{10}{2}=5;\\ & 0.\overline{2}=\mathrm{0.222...};\\ & {\left(0.2\right)}^2=0.04\\ & 0.04<0.2<\mathrm{0.22....}<5\\ & \text{Since}0.04\text{is}\text{the}\text{least,}\text{so}{\left(0.2\right)}^2\text{is}\text{the}\text{least}.\end{array}$$