Pneumatophores are specialised __________ in hydrophytes.

The correct option is roots.

Pneumatophores, also commonly known as respiratory or breathing roots, are specialized root structures found in certain plants, particularly those growing in waterlogged, anaerobic (oxygen-poor) soils such as mangrove swamps or hydrophytic environments.
Since waterlogged soils lack sufficient oxygen for normal root respiration, these roots grow vertically upwards, rising out of the water and mud into the air. The surface of these pneumatophores contains tiny pores called lenticels, which facilitate the exchange of gases, allowing the plant to absorb oxygen directly from the atmosphere and transport it to the submerged root system.