Which contains the strongest $H$-bond?

Hydrogen bonding plays a central role in the following phenomena:
$(A)$ Ice floats in water.
$(B)$ Higher Lewis basicity of primary amines than tertiary amines in aqueous solutions.
$(C)$ Formic acid is more acidic than acetic acid.
$(D)$ Dimerisation of acetic acid in benzene.

Which one among the following does not have the hydrogen bond?

The correct order of strength of hydrogen bonding in the following compounds is:

In which of the following compounds does hydrogen bonding occur?

Intramolecular hydrogen bonding is formed in