In C3 plants the first stable product is

Answer: Option C

The C₃ cycle is also known as the Calvin cycle. The plants that go through the Calvin cycle are called C₃ plants. It is the cycle of chemical reactions that occur in the chloroplast of the plant cell where the carbon from the carbon cycle is fixed into sugars.
3-phosphoglyceric acid is the first stable product of the Calvin cycle in C₃ plants.