I think its D. but I'm not sure The reason being is it's a prosses that doesn't require the "help" or "cooperation" of other cells and it only effects the one cell.
The intracellular communication is a type of communication which takes place within a cell or inside a cell. The cells communicate with each other or to itself through pathways which involves the molecules.
Since the intracellular represents within a cell, therefore, the movement of the molecule within a cell may be with cytoplasmic streaming, cargo vesicle transport or any other mechanism will represent the intracellular communication.
CO2 is returned to the atmosphere by all methods except photosynthesis. Through photosynthesis, a plant actually takes CO2 from the atmosphere and produces oxygen in return.
