This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid, Subject name: Surgery
[{'content': '26 year old male presents to OPD with a discrete thyroid swelling. On neck USG , an isolated cystic swelling of gland is seen. How much percentage will be the risk of malignancy? \nSelect and explain. \nA. 48%, B. 24%, C. 12%, D. 3%', 'role': 'user'}, {'content': "Answer: B \nExplanation: - This is a case of an isolated cystic swellings. Risk of malignancy in this case is 24%. - Risk of malignancies in thyroid swelling can be expressed as a factor of 12 known as 'rule of twelve' - Isolated Thyroid swelling: Solid 24% Cystic 12% - Dominant Thyroid swelling: Solid 12% Cystic 6% - Generalized Thyroid swelling: 3%", 'role': 'assistant'}]