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': 'An investigator is studying a new biomarker test to detect breast cancer at early stages. A randomized study is conducted to compare the new test to the current standard of care. mammography, among women over 50 years ol& They conclude that breast cancer patients whose cancer was identified by the biomarker lived on average 1.5 years longer than those whose cancers were identified by mammography. \nIf additional independent studies show that there truly was no difference in survival between the two groups, which of the following biases is most likely to have occurred? \nSelect and explain. \nA. Confounding, B. Insensitive test, C. Lead time bias, D. Measurement error', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]