The first stable product of the Calvin cycle is

Explanation

The correct option is 3-phosphoglycerate, as it is the first stable product formed during the Calvin cycle after carbon fixation. 1,3-biphosphoglycerate is an unstable intermediate formed later in the reduction phase. Glyceraldehyde-3-phosphate is produced after further reduction steps and is used for glucose synthesis. Ribulose-5-phosphate is an intermediate involved in the regeneration of ribulose-1,5-bisphosphate, not a direct product of carbon fixation.