Which of the following contains co-ordinate covalent bond?

Explanation

The Nitrogen atom in Ammonia, NH3 has a lone pair of electron which is given out or shared with the Hydrogen ion to form NH4+. Recall that coordinate covalent bond usually involves one of the two participating atoms or molecules donating the lone pair of electrons to be shared by the two atoms or molecules to bond. Therefore option C is the correct answer as ammonium ion is formed by dative bonding or coordinate-covalent bonding.