Which of the following is an example of regulatory law?

The correct choice is Internal Revenue Service regulations as they represent a form of regulatory law. Regulatory law consists of rules and regulations imposed by government agencies, which are created to enforce laws passed by legislative bodies. The IRS, as a federal agency, issues regulations to define and enforce tax laws established by Congress. These regulations provide the necessary details for how tax laws are applied in practice, influencing compliance actions for individuals and businesses alike.

In contrast, the United States Constitution serves as the foundational document of the federal legal framework and does not fall under regulatory law; it establishes the structure of government and the fundamental rights of citizens. Local city ordinances are specific to municipalities and pertain to local governance rather than broader regulatory processes. The U.S. Bankruptcy Code outlines federal bankruptcy law but is considered substantive law rather than regulatory law, as it establishes rights and duties rather than implementing regulations for enforcement by an agency.