This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'Rate limiting step in pyrimidine synthesis \nSelect and explain. \nA. Dihydro-orotase, B. Ornithine transcarbomoylase, C. Aspaate transcarbomoylase, D. Carbamoyl phosphate synthase-I', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ref-D.M.Vasudevan 7/e p506 Aspaatetranscarbamylase catalyses a committed step in pyrimidine metabolism by conveing carbamoyl phosphate into carbamoyl aspaate', 'role': 'assistant'}]