This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
[{'content': 'Nottingham Prognostic index for CA breast is:- \nSelect and explain. \nA. =(0.2 x size ) + grade + nodes, B. =(0.4 x size ) + grade + nodes, C. =(0.6 x size ) + grade + nodes, D. =(0.8 x size ) + grade + nodes', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Nottingham Prognostic index NPI =(0.2 x tumor size in cm ) + Tumor grade + LN stage Used to select patients for adjuvant treatmentQ', 'role': 'assistant'}]