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
Which one of the following statements, concerning persistent hyperplastic primary vitreous (PHPV) is not true ?a) It is generally unilateralb) Visual prognosis is usually goodc) It may calcifyd) It is most easily differentiated from retinoblastoma by the presence of exophthalmos or cataract 
Select and explain. 
A. abc, B. bcd, C. ac, D. bd
B: bcd
Answer: B: bcd 
Explanation: PHPV is almost always (90%) unilateral.
Visual prognosis is bad as neither conservative treatment nor surgery can improve visual acuity.
There is no calcification, which is a differentiating feature from retinoblastoma.
PHPV can be differentiated from retinoblastoma by presence of cataract in PHPV but not by exophthalmos.