explain the answer
(1) Pyramid of numbers in grassland is upright as when we go from lower trophic level to higher trophic level energy as well as number of organisms on each trophic level decreases. Producers are always greater than consumers. So, this option is incorrect.
(2) Fallow land is a land which is usually used for farming but for recovery of its fertility it is left with no crops for a session. So, it also doesn't show the given pyramid. This option is also incorrect.
(3) Pyramid of biomass in lake is spindle shaped as the biomass of diatoms and other producers is negligible as compared to biomass of small herbivorous fish. Carnivores that feed on herbivorous are very few in number and also have lesser biomass. So, this option is correct.
(4) Pyramid of energy is always upright as at higher trophic level only 10% energy is transferred. So, this is also incorrect option.
Hence, option (3) is correct answer for given pyramid.
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