Correct Option (d)
Reason : Vallisneria is at second stage of hydrosere. It starts orginating in a pond with colonisation of some phytoplanktons which forms the pioneer plant community. The stages are
Ist - Bacteria, blue-green algae and algae
IInd - Hydrilla, Potamogeton and Vallisneria
IIIrd - Nelumbo, Nymphaea, Trapa, Azolla and Wolffia
Correct Option (d) Reason : Vallisneria is at second stage of hydrosere. It starts orginating in a pond with colonisation of some phytoplanktons which forms the pioneer plant community. The stages are
Ist - Bacteria, blue-green algae and algae
IInd - Hydrilla, Potamogeton and Vallisneria
IIIrd - Nelumbo, Nymphaea, Trapa, Azolla and Wolffia
IVth - Typha and Sagitaria
Vth - Juncus and Cyperus
VIth - Salix and Populus, Almus.