This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Which is a common metabolic process in human as well as bacteria 
Select and explain. 
A. Purine synthesis, B. Nitrogen fixation, C. Mucolipid formation, D. Nonoxidative photophosphorylation
A: Purine synthesis
Answer: A: Purine synthesis 
Explanation: All forms of life (except protozoa) synthesize purine and pyrimidine nucleotides.