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: Physiology
[{'content': 'Heller and Paul double oxalate is also known as: \nSelect and explain. \nA. Sodium citrate, B. Sodium oxalate, C. Ethylene diamine tetra acetate (EDTA), D. Ammonium potassium oxalate', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Heller and Paul double oxalate is a combination of ammonium and potassium oxalate. It is an anticoagulant that is used commonly for hematological analyses. It does not cause shrinkage or enlargement of red blood cells. Ammonium oxalate cannot be used when test for urea are carried out. Ref: Diagnosis of Hemophilia and Bleeding Disorders, 2nd Edition, Page 11', 'role': 'assistant'}]