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': 'Squamous cell carcinoma can arise from-a) Long standing venous ulcersb) Chronic lupus vulgarisc) Rodent ulcerd) All of the above \nSelect and explain. \nA. ac, B. a, C. ab, D. bc', 'role': 'user'}, {'content': 'Answer: C \nExplanation: • It is a carcinoma of the cells of epidermis that usually migrate outwards to the surface.\n• Originate from prickle cell layer; Seen in > 40 years of age\n• MC skin cancer in darkly pigmented races\n• 2nd MC skin cancer in light skinned races\n• MC causative factor: Sunlight\n• MC site: Ears, cheeks, lower lip and back of hands', 'role': 'assistant'}]