The primary acceptor of CO2 - in C3 -plants is

Answer: Option C

The primary acceptor of CO₂ in C₃ plants is RuBP.
Ribulose 1,5 -bisphosphate (RuBP) is an organic substance that is involved in photosynthesis, notably as the principal CO₂ acceptor in plants.
It is a colourless anion, a double phosphate ester of the ketopentose (ketone-containing sugar with five carbon atoms) called ribulose.
During photorespiration, RuBP combines with O₂ to become 3-PGA and phosphoglycolic acid.