The correct answer is: B. grassland ecosystem.
A pyramid of biomass is a graphical representation of the biomass of organisms at each trophic level in a food chain. The biomass of an organism is its mass of living tissue. In a typical pyramid of biomass, the biomass of producers is greater than the biomass of consumers at each higher trophic level. This is because producers are able to capture energy from the sun and use it to create their own food, while consumers must consume other organisms to obtain energy.
In a grassland ecosystem, the biomass of producers is lower than the biomass of consumers at the next trophic level, the herbivores. This is because grasslands are often nutrient-poor ecosystems, and it is difficult for plants to grow and accumulate biomass. Herbivores, on the other hand, are able to obtain energy from the plants without having to invest as much energy in growing their own food. As a result, the biomass of herbivores is often greater than the biomass of producers in grassland ecosystems.
The other options are incorrect because they do not represent ecosystems in which the pyramid of biomass is inverted. In a forest ecosystem, the biomass of producers is greater than the biomass of consumers at each higher trophic level. In a fresh water ecosystem, the biomass of producers is also greater than the biomass of consumers at each higher trophic level. In a tundra ecosystem, the biomass of producers is very low, and the biomass of consumers is also low. However, the biomass of consumers is not greater than the biomass of producers in a tundra ecosystem.