The correct option is D Water Lily → Small fish → Crab → Bacteria
Ponds are aquatic freshwater ecosystems.
The main producers of any food chain are green plants, here, water lily. Small fishes consume them as food to obtain energy. Crab feeds on small fishes and this way the energy is passed on through several organisms present in the pond.
When all the organisms die, they fall on the seafloor. Decomposers like fungi and bacteria, act on them and add them as nutrients into the soil.