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
Most common cause of unilateral proptosis is 
Select and explain. 
A. Thyrotoxicosis, B. Retinoblastoma, C. Intraocular haemorrhage, D. Raised intracranial tension
A: Thyrotoxicosis
Answer: A: Thyrotoxicosis 
Explanation: A i.e. Thyrotoxicosis Grave's ophthalmopathy is most common cause of U/L or B/L proptosis in adults Q between age of 25-50 yrsQ