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: Skin
Lacy white lesion in mouth with pterygium is seen in : 
Select and explain. 
A. Psoriasis, B. Ptirysis alba, C. Lichen planus, D. Leprosy
C: Lichen planus
Answer: C: Lichen planus 
Explanation: C. Lichen planus