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: Surgery
[{'content': 'Male comes with acute scrotal pain. To differentiate between testicular torsion and epididymo-orchitis which is the best way \nSelect and explain. \nA. Angel sign, B. Prehn sign, C. Color Doppler, D. MRI', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Angel sign and prehn sign are not reliable.color Doppler is investigation of choice', 'role': 'assistant'}]