The correct answer is option a. only 10 percent of the energy at each trophic level is passed on to the next level.
The producers obtain their energy from the sunlight and convert it into usable form of energy for consumers. The primary consumers eat the plants, and obtain energy from the plants. On each trophic level, only 10 % energy is transferred to the succeeding one.
As only 10% of the energy is transferred to the next trophic level, the primary producers need to eat more plants in order to meet their energy requirement. This insufficiency of the energy transfer from one trophic level to another causes the decrease in the biomass on next level.
