Answer:
B = hydrogen bonding
Step-by-step explanation:
The water molecule consist of two hydrogen atom one oxygen atom. There is large electronegativity difference between oxygen and hydrogen. Both atoms are bonded through covalent bonds.
Covalent bond:
It is formed by the sharing of electron pair between bonded atoms.
The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive.
For example:
In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial negative. The partial positive end of one water molecule attracted towards the partial negative end of other moleucle. The attraction between them is called hydrogen bonding. In this way large mole are connected with each other. Hydrogen bonding is actually a weak bonding.