What is described as a set of permanent rules governing how the Executive Branch interprets congressional statutes?

The Code of Federal Regulations (CFR) is the correct answer because it serves as a comprehensive collection of the permanent rules and regulations created by federal agencies, including the Executive Branch, to implement and enforce laws enacted by Congress. The CFR organizes these regulations by topic and agency, making it easier for individuals and organizations to understand the regulatory framework. Each title in the CFR pertains to a specific area of federal regulation, with Title 14 specifically focusing on Aeronautics and Space, which relates to aviation safety but does not encompass the complete scope of executive regulations.

Federal Aviation Regulations (FAR) are a subset of the CFR that specifically deal with rules governing civil aviation, but they do not represent all the permanent rules covering how the Executive Branch operates in relation to congressional statutes. Hazardous Materials Regulations address a specific area of regulation concerning hazardous materials but do not represent the broader set of rules within the CFR. Thus, the CFR is the appropriate choice as it encompasses the entire regulatory system established by federal agencies in relation to congressional directives.