The compound which can form intramolecular hydrogen bonds is

Salicylaldehyde

The correct answer is option 2. Salicylaldehyde

The compound that can form an intramolecular hydrogen bond is (2) Salicylaldehyde.

Intramolecular hydrogen bonding is a type of hydrogen bonding that occurs between two groups on the same molecule. Salicylaldehyde is a molecule that contains two hydroxyl groups (-OH) that are close enough together to form an intramolecular hydrogen bond. The hydroxyl groups are both electron-rich, and they can donate a hydrogen atom to each other. This forms a hydrogen bond, which is a strong intermolecular force.

The other three compounds listed, m-hydroxybenzaldehyde, p-hydroxybenzaldehyde, and benzaldehyde, do not have two hydroxyl groups that are close enough together to form an intramolecular hydrogen bond. Therefore, the only compound that can form intramolecular hydrogen bonding is salicylaldehyde.

Here is a diagram of the intramolecular hydrogen bonding in salicylaldehyde:

The hydrogen atom from the hydroxyl group on the left is bonded to the oxygen atom on the right. This forms a hydrogen bond, which is a strong intermolecular force.