Answer: Option (a) is the correct answer.
Step-by-step explanation:
Hydrogen bonding is defined as a bonding which exists between a hydrogen atom and an electronegative atom like O, N and F.
But when H atom of a water molecule covalently bonds to the O in the same molecule then it will be a covalent bond and not a hydrogen bond.
As H atom of a water molecule has a partial positive charge so, it will interact with the O lone-pair electrons of a neighboring water molecule and then it will lead to the formation of a hydrogen bond.
Thus, we can conclude that the situation H atom of a water molecule interacts with the O lone-pair electrons of a neighboring water molecule, describes a hydrogen bond.