A graph between $1/[A]^2$ vs t is plotted below where [A] is conc of [A] at time t and $[A_o]$ is initial conc and K is the rate constant of a $Rx^n$ $nA\rightarrow$ product.What is the value of rate constant

Question

 

$\begin{array}{1 1}(a)\;20/3\times 10^{-6}&(b)\;10\times 10^{-6}\\(c)\;20\times 10^{-6}&(d)\;None\end{array}$