###Rationale: *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.

###Answer: OPTION B IS CORRECT.
###Question: Knudson's two stage hypothesis is for-
###Options:
A. Glaucoma
B. Retinoblastoma
C. Optic glioma
D. Meningioma
