This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Retina, 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: Ans. (b) RetinoblastomaRef Kanski 7/e, p. 520Deletion or inactivation of RB gene by two mutations (Knudson's two hit hypothesis) results in occurrence of retinoblastoma.