Final answer:
In C4 plants, carbon dioxide is captured in one cell and decarboxylation occurs in the adjacent cell.
Step-by-step explanation:
In C4 plants, carbon dioxide (CO2) is captured in the mesophyll cells and transferred to the adjacent bundle sheath cells where decarboxylation occurs. The bundle sheath cells have a higher concentration of carbon dioxide and contain an enzyme called RuBisCo that facilitates the fixation of carbon dioxide in the Calvin cycle.