In which ecosystem is the biomass of primary consumers greater than producers?

The correct option is Sea.

In most terrestrial ecosystems, such as forests, grasslands, and deserts, the pyramid of biomass is upright. This means that the biomass of producers (like trees, grasses, and shrubs) is significantly greater than the biomass of primary consumers (like herbivores). Producers in these environments are large, long-lived, and accumulate massive amounts of dry weight over time.

However, in aquatic ecosystems like the sea, this relationship is inverted, resulting in an inverted pyramid of biomass. In the sea, the primary producers are phytoplankton. Phytoplankton are microscopic, single-celled organisms that have an extremely small standing crop (biomass present at any given moment) because of their tiny size.
Despite their small biomass, phytoplankton have an exceptionally high rate of reproduction and turnover. They are rapidly consumed by primary consumers, which are mainly zooplankton and small fish. Because zooplankton and fish are larger and live much longer, they accumulate a larger standing biomass at any point in time compared to the phytoplankton they feed on.

Therefore, the biomass of primary consumers is greater than that of the producers in the Sea ecosystem.