This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Dental
[{'content': 'Pterygium of the nail is seen in \nSelect and explain. \nA. Lichen planus, B. Psoriasis, C. Tinea unguium, D. Alopecia areata', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pterygium of the nail is classically seen in lichen planus: Pterygium unguis (also known as "Dorsal pterygium") forms as a result of scarring between the proximal nailfold and matrix, with the classic example being lichen planus, though it has been repoed to occur as a result of sarcoidosis and Hansen\'s disease Ref Harrison 20th edition pg 1234', 'role': 'assistant'}]