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: Anatomy
[{'content': "Action affected in BENNET'S fraction of thumb? \nSelect and explain. \nA. Flexion of thumb, B. Abduction  of thumb, C. Opposition  of thumb, D. Adduction  of thumb", 'role': 'user'}, {'content': "Answer: C \nExplanation: Bennet's fraction is the fracture of base of 1st metacarpal. Opponens pollicis has its insertion to 1st metacarpal and hence its action is lost in the following fracture.", 'role': 'assistant'}]