Kindly solve Q 96 and explain in detail

Dear student, Oxaloacetate (OAA), malate, and aspartate (Asp) serve as substrates for the C4 cycle that help in the CO2 concentrating mechanism of C4 photosynthesis. In this cycle, OAA is the immediate, short-lived, product of the initial CO2 fixation step in C4 leaf mesophyll cells. The malate and Asp, which are formed from the rapid conversion of OAA, are the organic acids delivered to the sites of carbon reduction in the bundle-sheath cells of the leaf, where they are decarboxylated, while the released CO2 used to make carbohydrates. So pyruvic acid is odd one out and hence option 4 is correct. Thanks and regards.