Intramolecular hydrogen bonding is present in:

Intramolecular hydrogen bonding occurs within the same molecule.In $o$ -nitrophenol, the $-\text{OH}$ group and $-{\text{NO}}_2$ group are adjacent (ortho position). The hydrogen of $-\text{OH}$ forms a bond with the oxygen of $-{\text{NO}}_2$ within the same molecule.In $p$ -nitrophenol and $m$ -nitrophenol, the groups are too far apart, so they form intermolecular hydrogen bonds with other molecules.