Dative covalent bond IB 2011

answer is D
can someone explain? I know what a dative covalent is but still couldn’t figure out how to approach this question


Cl⁻ and H2O are weak field ligands, and NH3 is a strong field ligand
i think we can answer the question without knowing that
since the ligand needs to form a dative bond it needs to be able to provide 2e⁻ to form the bond, and option 1) 2) and 3) have a complete octet and at least one lone pair of electrons, so if they will be bonded to another atom, they need to provide both e⁻ from their lone pair