Which of the following is the factorization of the polynomial ${\mathrm{a}}^3-0.064$?

The given polynomial is ${\mathrm{a}}^3-0.064.$ 
The given polynomial can be written as ${\mathrm{a}}^3-{(0.4)}^3.$ 
We know that ${\mathrm{a}}^3-{\mathrm{b}}^3=(\mathrm{a}-\mathrm{b})({\mathrm{a}}^2+\mathrm{ab}+{\mathrm{b}}^2).$  

Therefore, using this formula with $\mathrm{a}=\mathrm{a}\text{ and }\mathrm{b}=0.4,$  

we get,

${\mathrm{a}}^3-0.064=(\mathrm{a}-0.4)({\left(\mathrm{a}\right)}^2+\mathrm{a}\times 0.4+{\left(0.4\right)}^2)$  

$\Rightarrow {\mathrm{a}}^3-0.064=(\mathrm{a}-0.4)({\mathrm{a}}^2+0.4\mathrm{a}+0.16)$ 
Therefore the factorization of the polynomial ${\mathrm{a}}^3-0.064$ is $(\mathrm{a}-0.4)({\mathrm{a}}^2+0.4\mathrm{a}+0.16).$