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': 'There was a sudden increases in the size of thyroid swelling along with pain. Most likely cause is ? \nSelect and explain. \nA. Hemorrhage within the cyst (Thyroid), B. Malignant change, C. Nodular goiter, D. Colloid goiter', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Hemorrhage within the cyst (thyroid)", 'role': 'assistant'}]