Which of the following is a type of penalty for violating OSSF regulations?

A penalty for violating OSSF regulations can indeed include various forms of enforcement actions designed to address non-compliance and ensure adherence to environmental and public health standards. An injunction serves as a legal remedy that prohibits a party from continuing a certain action, such as using an improperly functioning septic system. This action is typically taken by a court in response to violations that pose a threat to public health or the environment, therefore making it a suitable and serious legal consequence for such infractions.

In contrast, while informal warnings and license suspensions can also be punitive measures, they might not carry the same level of urgency or legal enforceability as an injunction does. Community service is generally not a recognized or appropriate penalty within the framework of OSSF violations, as the focus is more on ensuring proper compliance with sewage regulations rather than imposing community service obligations.