In the light-independent stage of photosynthesis, the CO₂ combines with _ to form an unstable 6-carbon intermediate.

Explanation

In the light-independent stage of photosynthesis, also known as the Calvin cycle or dark reactions, carbon dioxide (CO2) combines with a five-carbon sugar called ribulose-1,5-bisphosphate (RuBP) to form an unstable 6-carbon intermediate. The enzyme responsible for this initial reaction is ribulose-1,5-bisphosphate carboxylase/oxygenase, commonly abbreviated as Rubisco.