The correct option is B C.N.=6,O.N.=+4
The complex dissociate as [Pt(Cl)6]2−and 2NH+4.
The central metal atom in coordination sphere is attached to 6 Cl− ligands. Thus, the coordination number is 6.
Oxidation state of Pt in coordination compound is
x+(−1)×6=−2
x−6=−2
x=+4
Hence, option (b) is correct.