What occurs when a class is included after being declared?

When a class is included after being declared in Puppet, it gets executed, leading to the application of its resources and defined behaviors. This execution results in producing an output, which reflects the defined configuration meant to be applied to a specific node or system.

The inclusion of a class triggers Puppet's evaluation process to apply the class's resources immediately and may also lead to changes in the system configuration, depending on what was defined within the class. This is an essential mechanism in Puppet, as it allows for modular and reusable code by enabling various classes to be applied as needed.

The other choices suggest different behaviors that do not accurately describe what happens upon including a declared class. Instead, including a class always leads to its execution unless explicitly prevented by conditions not stated in the question.