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
One of the early symptoms of orbital involvement by basal cell carcinoma of the lid is: 
Select and explain. 
A. Diplopia, B. Defective vision, C. Proptosis, D. Severe pain
A: Diplopia
Answer: A: Diplopia 
Explanation: Ans. Diplopia