When CO2 is added to PEP, the first stable product synthesized is

1. pyruvate

2. glyceraldehyde-3-phosphate

3. phosphoglycerate

4. oxaloacetate

(d) Oxaloacetate is a four carbon compound formed in Ccycle and is a first stable product, that is why such plants are called C4 plants.
 
Rest of the options are incorrect as because
(a) Pyruvate is formed in glycolysis.
(b) Glyceraldehyde-3-phosphateis also an intermediate compound of glycolysis.
(c) Phosphoglycerate is also an intermediate compound of glycolysis.
Page 219, XI NCERT