An inverted pyramid of biomass occurs in:

The correct answer is Option (4) → Lake

Option (4) Lake — Correct. NCERT gives the sea as its example of an inverted pyramid of biomass. A lake is also a water body: its producers are tiny phytoplankton with a small standing biomass, while the fish that feed on them build up a larger biomass. Of the four options, only the lake is an aquatic ecosystem, so it is the answer.

NCERT Extract:
Ecological Pyramids – “… In most ecosystems, all the pyramids, of number, of energy and biomass are upright, i.e., producers are more in number and biomass than the herbivores, and herbivores are more in number and biomass than the carnivores. Also energy at a lower trophic level is always more than at a higher level. There are exceptions to this generalisation: … The pyramid of biomass in sea is generally inverted because the biomass of fishes far exceeds that of phytoplankton.”