The following statements refer to a pyramid of energy.
I. Some material is not assimilated by each trophic level.
II. Energy transformations are never 100 % efficient.
III. Heat is lost during photosynthesis.
Which of the statements give the reason why a pyramid of energy is narrower at the top than at the bottom?
A. I only
B. I and II only
C. II and III only
D. I, II and III.

B. I and II only

Explanation:

Pyramid of energy is a model used to depict the flow of energy from one trophic level or feeding level to the next in an ecosystem. It's a diagram that compares the energy used by organisms at each trophic level of the food chain. The pyramid of energy must never be inverted or turned upside down.

The units used in the construction of pyramids of energy is kilocalories (kcal) or energy per area per time (Jm-²year-¹).

The following statements refer to a pyramid of energy;

I. Some material is not assimilated by each trophic level.

II. Energy transformations are never 100% efficient.

b is the best answer for this question.