In chlorophyll, Mg is present as a cation and binds with four N atoms. Vitamin is also known as cyanocobalamine and and contains cobalt. Cisplatin is used as an anti-cancer drug and is a coordination compound of platinum. Grubbs catalyst is a compound of Ruthenium.
Therefore, the correct order is:
A(IV), B-(III), (C)-(II), (D)-(I)