Concept:Interdependence of cells means that specialised cells perform different functions and rely on each other to survive.
Explanation:Volvox is a multicellular green alga with a hollow colonial body.
Its cells show division of labour.
Some cells are somatic and handle movement and nutrition, while others are specialised for reproduction.
These cells cannot survive separately because each group depends on the other for the life of the whole colony.
Spirogyra is a filamentous alga whose identical cells are largely independent.
Both Eudorina and Pandorina are simpler colonies with less cell specialisation.
Hence, interdependence is most clearly maintained in Volvox.
Answer:B. Volvox