The primary acceptor during CO2 fixation in C3 plants is

Explanation

In C3 plants, the Calvin cycle is the series of reactions that occur in the light-independent phase of photosynthesis. The primary acceptor of CO2 during this cycle is Ribulose bisphosphate (RuBP). RuBP combines with CO2 to form a 6-carbon intermediate, which quickly splits into two molecules of 3-phosphoglycerate. This is a key step in the process of carbon fixation. Glycolate, on the other hand, is related to photorespiration, not carbon fixation. Phosphoenolpyruvate (PEP) serves as the primary CO2 acceptor in C4 plants, not C3. Triosephosphate is a molecule produced later in the Calvin cycle, not during the initial fixation of CO2.