A container holds 40 g of argon-40 $\left( {_{{\text{18}}}^{{\text{40}}}{\text{Ar}}} \right)$ and 8 g of helium-4 $\left( {_{\text{2}}^{\text{4}}{\text{He}}} \right)$.

What is the $\frac{{{\text{number of atoms of argon}}}}{{{\text{number of atoms of helium}}}}$ in the container?

A.     $\frac{1}{2}$

B.     $\frac{2}{9}$

C.     $\frac{2}{1}$

D.     $\frac{9}{2}$

A