Pyramid of energy is always upright because:

The correct answer is Option (3) → Some energy is lost when we move from one trophic level below to next trophic level above

Option (1) Energy flows unidirectionally — Incorrect. Energy does flow one way, from the sun to producers to consumers. But one-way flow alone would not make each level smaller; the loss at each step does.

Option (2) The number of organisms at different trophic levels do not affect energy application. — Incorrect. This says nothing about why each level has less energy than the one below.

Option (3) Some energy is lost when we move from one trophic level below to next trophic level above — Correct. At every transfer some energy is lost as heat, so each higher level always has less, and the pyramid can never be inverted.

Option (4) Energy largely depends on the biomass at the base trophic level — Incorrect. Biomass can be smaller at the base, as in the sea, where the pyramid of biomass is inverted. The pyramid of energy stays upright even there.

NCERT Extract:
Ecological Pyramids – …