For a binomial variate X with $n=6,$ if $P(X=2)=9\;P(X=4),$ then its variance is :

Question

$$\begin {array} {1 1} (a)\;\frac{8}{9} & \quad (b)\;\frac{1}{4} \\ (c)\;\frac{9}{8} & \quad (d)\;4 \end {array}$$