The correct answer is: B. Resolution
Resolution is a rule of inference in propositional logic. It is used to prove that a proposition is true if two other propositions, each of which is the negation of a disjunction of two literals, are true.
For example, if we know that $p \lor q$ and $\neg p \lor r$ are true, then we can use resolution to prove that $q \lor r$ is true.
Resolution is a very powerful rule of inference, and it is used in many different areas of mathematics and computer science.
A. Reference is not a rule of inference. It is a process of finding and identifying information that is relevant to a particular topic.
C. Reform is not a rule of inference. It is a process of changing something in order to make it better or more effective.
D. None of the mentioned is not the correct answer. The correct answer is B. Resolution.