Statement A: The most abundantly present protein on this planet is a bifunctional enzyme. Statement B: PEP carboxylase catalyses not only carboxylation but also oxygenation.

Rubisco (Ribulose bisphosphate carboxylase oxygenase) is the most abundantly present enzyme on this planet. It catalyses carboxylation as well as oxygenation and described as bifunctional enzyme. PEP carboxylase catalyses only carboxylation to form oxaloacetic acid from Phosphoenolpyruvic acid.