This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
[{'content': '% of cold thyroid nodule which are malignant are \nSelect and explain. \nA. 5, B. 15, C. 20, D. 50', 'role': 'user'}, {'content': 'Answer: C \nExplanation: cold nodule is nonfunctioning nodule,it is not take up isotope, under active 20% cold nodule are malignant ref ;(page no;463) 5th edition of SRB&;S Manual of SURGERY', 'role': 'assistant'}]