Explanation
The primary acceptor of carbon dioxide in photosynthesis is Ribulose 1, 5-bisphosphate (RuBP), which is a 5-carbon sugar molecule that serves as a substrate for the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco).
Rubisco catalyzes the first step of the carbon fixation pathway in photosynthesis, which involves the addition of carbon dioxide to RuBP to form a six-carbon intermediate that immediately splits into two molecules of 3-phosphoglycerate (3-PGA).
Therefore, the correct answer is C: Ribulose 1, 5- Bisphosphate. It serves as the primary acceptor of carbon dioxide in the Calvin cycle of photosynthesis.
