$HgCl_2$ and $I_2$ both when dissolved in water containing $I^–$ ions pair of species formed is :

Question

( A ) $HgI_2, I^-$
( B ) $Hg_2I_2, I^-$
( C ) $HgI_4^{2-}, I^-_3$
( D ) $HgI_2, I^-_3$