Answer: The correct answer is- d. producers.
Biomass can be described as the amount of organic matter or living matter that is present in an organism within an ecosystem.
Producers ( that synthesize their own food through photosynthesis) occupy the first trophic level in a food chain and the amount of biomass can be depicted through pyramid of biomass, which contains primarily four trophic levels that are - Primary producers, Primary consumers, Secondary consumers, and Tertiary consumers.
Producers ( or primary producers) have maximum biomass because they occupy the first level in the food chain and only 10 % of the energy ( biomass) is transferred to the next trophic level as remaining is utilized in cellular processes and lost as heat in the surrounding.