What causes the H bonds in water molecules to last only 10^-11 sec?

[scientiavore]

I have thought of two possible explanations:

a) Energy required to break H bonds = Energy released when H bonds form.
There is a "constant" equilibrium in the system, meaning, some water molecules form H bonds, releasing energy to the environment which causes other water molecules to loose their H bonds, and this could on forever if isolated.

b) The H bonds last so little because the e- density in the water molecules change, the partially charged zones of the molecule are not constant and they change over time breaking the H bonds between the water molecules.

Which one is correct(if any)?

 

[Kushal]

i would suggest that it is because the water molecules are constantly moving around because they possesses kinetic energy.