In coordination compounds, the counter ions can react to give another product but the complex ion will not split in a solution.
Here, when one mole of a complex given when reacted with AgNO3 then the maximum counter ion compound will give the maximum amount of AgCl.
Hence, [Co(NH3)6]Cl3 having a maximum number of 3 counter ions in the given options will produce more amount of AgCl. [Co(NH3)6]Cl3→[Co(NH3)6]3+(aq)+3Cl−(aq) AgNO3+Cl−(aq)→AgCl+NO3−(aq)