Multiple choice Which of the following is the first intermediate formed during photosynthesis? Fructose 1,6-diphosphate Ribulose 1,5-diphosphate Xylulose 5-phosphate Phosphoglyceraldehyde - Reveal answer Fill a bubble to check yourself D Correct answer Explanation The first stable product is a 3-carbon compound called as phosphoglyceraldehyde. Hence, it is named C3 cycle.