Number of unit cells in $4\;g$ of $\times$ (atomic mass =40) Which crystallize in bcc pattern is $(N_A= Avogadro \; number)$

Question

$\begin{array}{1 1} 0.1 \;N_A \\ 2.1 \;N_A \\ \large\frac{0.1}{2} \;N_A \\ 2N_A \end{array}$