Hydrophytes are water loving plants and grow in aquatic environments. Hydrophytes grow partially or completely submerged in water. In these plants mechanical tissue is absent. They have no extensive vascular tissues, poorly developed mesophyll and reduced root systems. Xylem is poorly developed or absent.
Thus, the correct answer is option C..

Characteristics of Hydrophytes
Hydrophytes are plants that are adapted to live in aquatic environments, either partially or completely submerged in water. They have specific adaptations that allow them to survive and thrive in these conditions. One of the characteristic features of hydrophytes is a reduction in vascular tissue, mechanical tissue, and cuticle.

Reduction in Vascular Tissue
Vascular tissue in plants is responsible for the transport of water, minerals, and nutrients throughout the plant. In hydrophytes, there is a reduction in the amount of vascular tissue, particularly in the stem and leaves. This reduction is due to the availability of water in aquatic environments. Since water is readily available, hydrophytes do not need to invest as much energy in developing extensive vascular tissue for water uptake and transport.

Reduction in Mechanical Tissue
Mechanical tissue in plants provides support and structure, allowing them to withstand mechanical stresses such as wind or weight. In hydrophytes, there is a reduction in mechanical tissue, particularly in the stem and leaves. This reduction is due to the buoyancy provided by the water. Hydrophytes do not need to invest as much energy in developing strong and rigid tissues to withstand mechanical stresses because the surrounding water supports them.

Reduction in Cuticle
The cuticle is a waxy layer present on the surface of leaves and stems that helps reduce water loss through evaporation. In hydrophytes, there is a reduction in the cuticle layer. This reduction is because hydrophytes are surrounded by water, which provides a constant supply of moisture. Therefore, hydrophytes do not need to invest as much energy in developing a thick cuticle layer to prevent water loss.

Explanation of the Correct Answer
Based on the characteristics described above, the reduction in vascular tissue, mechanical tissue, and cuticle is characteristic of hydrophytes. Hydrophytes have adaptations that allow them to live in aquatic environments, where water is readily available and provides support. Therefore, option 'C' - hydrophytes is the correct answer to the question.

Conclusion
Hydrophytes, or aquatic plants, have specific adaptations to survive in water-filled environments. These adaptations include a reduction in vascular tissue, mechanical tissue, and cuticle. These adaptations allow hydrophytes to efficiently obtain water and nutrients, as well as withstand the mechanical stresses of their aquatic habitats.