Final answer:
The UNSAFE permission set allows code to access local and network resources, the registry, and environment variables.
Step-by-step explanation:
The permission set that allows code to access local and network resources, the registry, and environment variables is the UNSAFE permission set. The UNSAFE permission set is the most permissive permission set in the .NET Framework, granting code full trust to perform potentially harmful actions. This includes accessing local and network resources, modifying the registry, and reading/manipulating environment variables.