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: Ophthalmology
Corneal vascularisation is/are caused by: 
Select and explain. 
A. Graft rejection, B. Chemical burn, C. Contact lens use, D. All
D: All
Answer: D: All 
Explanation: Ans. A, B and C