This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors, Subject name: Ophthalmology
Knudson's two stage hypothesis is for- 
Select and explain. 
A. Glaucoma, B. Retinoblastoma, C. Optic glioma, D. Meningioma
B: Retinoblastoma
Answer: B: Retinoblastoma 
Explanation: *Deletion or inactivation of RB gene by two mutations (knudson's two hit hypothesis) results in occurence of retinoblastoma. Ref: Khurana 7th/e p.314.