$\begin{array}{1 1}(a)\;I_2\text{ is Lewis base and }I^-\text{ as Lewis acid}\\(b)\; I_2\text{ is Lewis base and }I^-\text{ as Lewis base}\\(c)\;I_3^-\text{ itself behaves as amphoteric anion}\\(d)\;I_3^-\text{ does not exist}\end{array}$
