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: Social & Preventive Medicine
[{'content': 'All of the following are continuous variable   except \nSelect and explain. \nA. Weight in kgs, B. Height in cm, C. Hb levels in mg/dl, D. Human blood group', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Human blood group (A,B,AB,O) is a type of discrete variale.', 'role': 'assistant'}]