The answer is: A. H2O.
Water forms hydrogen bonds.
Hydrogen bond (intermolecular force) is an electrostatic attraction between two polar groups that occurs when a hydrogen atom (H), covalently bound to a highly electronegative atom such as flourine (F), oxygen (O) and nitrogen (N) atoms.
That is because oxygen has largest electronegativity and smallest atomic radius of all elements in group. Other elements in this group do not form hydrogen bonds.
