Which one of the following is submerged floating hydrophyte ?

The correct answer is Utricularia bifida

Concept:

• Hydrophytes are plants that grow in water or in soil that is permanently saturated with water. They are classified into different categories based on their mode of growth and adaptation, such as free-floating, submerged, and emergent hydrophytes.
• Submerged floating hydrophyte plants remain completely submerged in water and are not rooted in the soil. They are buoyant, as they float freely below the water's surface. These plants have specialized adaptations, such as feathery or thin leaves to absorb nutrients and gases directly from water.
• Utricularia bifida is an example of a submerged floating hydrophyte. Utricularia species are also known as bladderworts and are carnivorous plants. They possess small bladder-like structures that trap tiny aquatic organisms for nutrients.

Other Options:

• Ipomoea sp.: Ipomoea species are primarily terrestrial or climbers, and they are not hydrophytes. Some species, like Ipomoea aquatica (water spinach), are semi-aquatic but not submerged floating hydrophytes
• Euphorbia sp.: Euphorbia species are typically terrestrial plants and are not adapted to aquatic environments. 
• Dentella repens: Dentella repens is a creeping plant that grows in damp environments. It can be found near water bodies but does not remain submerged in water.