In ITIL 4, incident models provide predefined steps for handling incidents, including the roles and responsibilities of third parties. It is important that these models define how and when third parties are involved in incident management, ensuring their contribution is clear and that the process is efficient and effective.
Excluding third parties (Option A) is incorrect, as third parties often play a critical role, especially in complex services that involve external providers.
Delegating incident management (Option C) to third parties is only appropriate in specific contexts and not a general best practice.
While formalizing interactions (Option D) is important, it is secondary to clearly defining third-party roles in incident models.