In Binomial distribution, if $E(X)=40 $ and $V(X)=8, $ then value of $P(X=1), $ is :

$\frac{8}{5^{48}}$ $\frac{2}{5^{49}}$ $\frac{3}{5^{49}}$ $\frac{7}{5^{49}}$

$\frac{8}{5^{48}}$