The correct option is B For making compulsory education a success, it should be free.
Option B: It's mentioned in the topic sentence: "It must be realized to make compulsory education a success, it is absolutely necessary to make it entirely free."
A topic sentence usually presents the main idea of the passage.
The central argument of this passage is "For making compulsory education a success, it should be free."
It is supported by other instances in the passage as well:
Free education is necessary because education is a basic and fundamental right.
"Since education is a fundamental civil and human right and basic to the health of the body politics, funds must be found for the purpose whatever the cost of the scheme."
Also, we need to give priority to education and adopt measures that will help raise funds for free education."If we consider educational and cultural activities to be important, funds will be forthcoming. What we have to do is to rearrange our priority."
Hence OPTION B is correct.
Options A, C and D are incorrect because the passage is not about these aspects of education: education should be made compulsory (it should be, but the passage is about free education), mass education is not possible in India (some people will always say this, but the passage here is about free education), and priority should be given to education (this is a tool to achieve funds for education).