In this question, the correct order of flow of energy in an aquatic ecosystem is Phytoplankton → zooplankton → fish → mammal.
<h3>What do you mean by an Ecosystem?</h3>
An environment may be defined as the complex of physical, chemical, and biotic factors (such as climate, soil, and living things) that act upon an organism or an ecological community and ultimately determine its form and survival.
The flow of energy in an aquatic ecosystem depends on the phytoplankton which are known as the producers of an aquatic ecosystem.
Therefore, the correct order of flow of energy in an aquatic ecosystem is described above. Hence, the correct option is B.
To learn more about the Aquatic ecosystem, refer to the link:
brainly.com/question/842527