Comprehensive and Detailed Step-by-Step Explanation:

Incident response policies must provide clear and actionable steps to ensure effective handling of incidents. Notification requirements are critical to ensure timely communication with stakeholders during an incident.

A. A description of testing methodology: While testing is important, it is typically addressed in incident response plans, not the policy itself.

B. Notification requirements: This is the BEST answer as it ensures that key stakeholders are informed promptly, allowing for coordination and mitigation efforts.

C. An infrastructure diagram: This is useful for understanding system architecture but is not a core policy requirement.

D. Recovery time objectives (RTOs): RTOs are part of business continuity and disaster recovery plans, not incident response policies.