As regards to intraocular retinoblastoma, which one of the following statements is false –
Very important facts about sporadic retinoblastoma -


It is not inherited (not acquired from parents)
But it is heritable (1/3rd cases can transmit the gene to their offspring’s).


Ultrasound and CT scan are able to detect an intraocular mass with calcification which is pathognomonic of retinoblastoma.
The prognosis for preservation of the eye with at least some useful vision can be assessed with some degrees of success using classification such as Reese-Ellsworth system and the Esson prognosis classification.

Option a is controversial

Different textbook have mentioned different percentage for sporadic and hereditary retinoblastoma - "95% of these retinoblastomas has no family history".  —Neonatal emergencies
"The majority of retinoblastoma cases (90%) arise sporadically in the tissues of the affected proband or the parental germ line". ___ Carlos
"The great majority of retinoblastoma (85%) are sporadic tumors". — Eye pathalogy
"The majority of retinoblastoma is sporadic (60%)".  — Blue prints pediatrics 
"Nonheritable retinoblastoma accounts for about 60% of cases". -  Tumors of the eye by H. cher
"Non- hereditary or sporadic cases account for 60% of all cases". ___Khurana
"60% of all retinoblastoma are sporadic".  — Human heredity



So, some books have mentioned that 90-95% cases of retinoblastoma are sporadic. While others have mentioned that 60-65% cases of retinoblastoma are sporadic.
Therefore, I had to do extensive work on this and found something to clear your doubts.
Most of the books have considered sporadic cases and non- heritable cases as the same. Which is not the cases. I have read many books on genetics of retinoblastoma. First read the following statement

"About 40% of all retinoblastoma patients have a germ line mutation in the Rb gene, although 7% have a positive family history. Therefore, most patients with heritable retinoblastoma are sporadic cases with new germ line mutation" .  — Human heredity with InfoTech.

Therefore, though the chances of gene transmission is more in hereditary retinoblastoma, most of the heritable retinoblastoma are sporadic (and this is the answer of our question).
After reading this statement you can easily get the following facts-


Sporadic retinoblastoma are those in which there is no family history of retinoblastoma
Non - hereditary cases are those in which the RB gene mutation is not acquired from parents
Hereditary cases are those in which the RB gene mutation is acquired from parents (this also includes heritable sporadic cases).


Thus, sporadic retinoblastoma and non - hereditary retinoblastoma are not synonymous :-


Sporadic cases = Nonhereditary cases + Hereditary cases with no positive family history of retinoblastoma.


After reading all these you can easily understand that the percentage of sporadic retinoblastoma will always be more than non- hereditary retinoblastoma. Now you read the frequencies :-


Hereditary cases  → 40% of all retinoblastomas
Non-hereditary cases → 60% of all retinoblastomas
Sporadic cases → 90-95% of all retinoblastomas
94% of cases are sporadic
Patients with sporadic retinoblastoma do not pass their genes to their offsprings
Calcification in the tumor can be detected on ultrasound scan
Reese–Ellsworth classification is useful in predicting visual prognosis following radiotherapy