If * is a binary operation defined in $Q^+$ as $a*b=\large\frac{ab}{3}$, then the inverse element of 4*6 is ?

Question

$\begin{array}{1 1}\large\frac{9}{8} \\\large\frac{8}{9} \\ \large\frac{2}{3} \\ \large\frac{3}{2}\end{array}$