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: Pathology
[{'content': 'Molecular classification of breast cancer is based on - \nSelect and explain. \nA. Gene expression profiling, B. Expression of hormone receptors (ER/PR), C. Serum hormone levels, D. In-vitro response to chemotherapeutic agents', 'role': 'user'}, {'content': 'Answer: A \nExplanation: . Gene expression profiling', 'role': 'assistant'}]