Which of the following is NOT an incident response control listed under NIST 800-61?

The correct choice indicates that "IR-9 (Monitoring)" is not an incident response control listed under NIST 800-61. NIST SP 800-61 focuses on incident response and provides a structured approach to handle incidents effectively. Within its framework, various incident response controls are outlined, such as handling and response plan responsibilities, but monitoring specifically tied to incidents is not categorized under a specific IR control number in this document.

The other options represent established controls within the NIST framework. For instance, "IR-4 (Handling)" relates to the processes that should be enacted when incidents occur, ensuring teams know how to manage them. "IR-8 (Response Plan)" details the expectations for planning and preparedness before incidents arise, which is crucial for having a well-organized plan in place. On the other hand, "IR-5 (Monitoring)" would specifically relate to the measures taken to observe and detect incidents effectively. Thus, IR-9 is not recognized as an incident response control structure within the guidelines, confirming its status as the answer to the question.