The correct match is A-2, B-3, C-4, D-1.

• is an example of linkage isomerism. It arises in a compound containing ambidentate ligand.

• is an example of ionisation isomerism. This form of isomerism arises when the counter ion in a complex salt is itself a potential ligand and can displace a ligand which can become counter ion.

• is an example of coordination isomerism. It arises from interchange of ligands between cationic and anionic entities of different metal ions present in a complex.

• is an example of solvate isomerism, in this isomerism water is involved as a solvent.