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 statements regarding cross over studies are true, except \nSelect and explain. \nA. Not suitable if the disease doesn't change radically during the study, B. All patients receive the new therapy, C. It is not suitable if the drug of interest cures the disease, D. None", 'role': 'user'}, {'content': "Answer: A \nExplanation: Cross over study is suitable if the disease doesn't change radically during the study. In cross over study all patients recieve both new treatment and current standard treatment but are randomised to recieve them in different orders .", 'role': 'assistant'}]