Assertion: In a marine aquatic ecosystem, the biomass of phytoplanktons (producers) at any given time, is lower than the biomass of zooplanktons (primary consumers).
Reason: Phytoplanktons are consumed almost as rapidly as they are formed and thus have shorter life spans.

Answer

A

Explanation

In a marine aquatic ecosystem, the biomass of phytoplanktons (producers) is smaller than that of zooplanktons (primary consumers) and the biomass of zooplanktons is smaller than that of secondary consumers. This results in the inverted pyramid of biomass in an aquatic ecosystem. This shape is the consequence of the very short life spans of phytoplanktons, which are consumed almost as rapidly as they are formed.