Which of the following describes legislative rules?

Legislative rules are formal regulations created by an administrative agency that have the force of law. They are designed to implement specific statutory provisions passed by the legislature. This means that when a law is enacted, the agency responsible for enforcing that law may develop legislative rules to provide more detailed guidance on how the law will be applied in practice. These rules are necessary to fill in details and provide clarity on how the legislative intent will be operationalized.

In contrast, the other options suggest characteristics that do not accurately represent legislative rules. For example, describing them as optional and advisory misrepresents their mandatory nature. Clarifying existing regulations is more indicative of interpretive rules rather than legislative rules, which seek to create new regulatory frameworks. Similarly, the notion of providing flexibility in rule application is more akin to policies or guidance documents, rather than the definitive structure that legislative rules embody. Thus, the distinguishing feature of legislative rules is their role in implementing specific regulatory statutes effectively, solidifying option B as the correct answer.