A complex compound of $Co^{3+}$ with molecular formula $CoCl_x.yNH_3$ gives a total of 3 ions when dissolved in water. How many $Cl^{-}$ ions satisfy both primary and secondary valencies in this complex ?

Question

\[\begin {array} {1 1} (a)\;3 & \quad (b)\;1 \\ (c)\;4 & \quad (d)\;zero \end {array}\]