Answer:
The correct answer is - RuBP.
Step-by-step explanation:
In calvin cycle or C3 cycle there is only one carbon compound present or enter in the cycle is carbon dioxide which is enters through stomata and move into stoma of chloroplast. It is the site of of the C3 cycle.
In calvin cycle energy used to reduce 3-phosphoglyceric acid to produce glyceraldehyde-3 phosphate which result in generation of the RuBP that accepts the CO2 from the air to attached with RuBISCO.