AgCN form isonitrile because Ag—CN is covalent and hence it can't form cyanide ions in solution

But HCN is also very weak electrolyte and can't dissociate into cyanide ions. Hence option 4 should be correct.

According to answer key option 3 is correct

@BongoMan @Swan @Gaurav @harikrishnan could someone please help me

@HarjotDhillon Tbh I don't check the extent of ionisation in questions of ambidentate ligands. Just if the source of nucleophile is ionic or covalent. I really don't know any better. Sorry! @YusufHasan bhaiya might help you with this