The correct answer is D. breakthrough.
A breakthrough is a significant and important advance in a particular area of knowledge or technology. In the context of the question, the new education policy provides a useful breakthrough for the planners to remove illiteracy. This is because the policy includes a number of innovative and effective measures to address the problem of illiteracy, such as providing free education to all children, training teachers in new methods of teaching, and establishing special schools for children with learning disabilities. These measures have the potential to make a significant difference in the lives of millions of children and adults who are currently illiterate.
The other options are not as relevant to the question. A break-in is an illegal entry into a building or other structure. A breakaway is a sudden and unexpected separation from something larger or more powerful. A break up is the act of separating or dividing something into smaller parts.
I hope this explanation is helpful. Please let me know if you have any other questions.