The correct option is D Aerenchyma
Parenchyma cells carry out many function as forming chlorophyll containing cells, storage cells. As per the function the shape, size of a parenchyma cell changes. In aquatic plants, parenchyma cell possess large air filled cavities and air filled intercellular spaces. These cells give buoyancy to plant to float in water. Such cells are then called as aerenchyma.
Therefore, the correct answer is option D.