The best indicator that information assets are classified accurately is appropriate prioritization of information risk treatment. Information asset classification is the process of assigning a level of sensitivity or criticality to information assets based on their value, impact, and legal or regulatory requirements. The purpose of information asset classification is to facilitate the identification and protection of information assets according to their importance and risk exposure. Therefore, if information assets are classified accurately, the organization can prioritize the information risk treatment activities and allocate the resources accordingly. The other options are not direct indicators of information asset classification accuracy, although they may be influenced by it. References = CISM Review Manual 15th Edition, page 671; CISM Review Questions, Answers & Explanations Database - 12 Month Subscription, Question ID: 1031

Security policy provisions are the statements or rules that define the information security objectives, principles, roles and responsibilities, and requirements for the organization. Security policy provisions must be established to maintain an effective information security governance framework, as they provide the foundation and direction for the information security activities and processes within the organization. Security policy provisions also help to align the information security governance framework with the business strategy and objectives, and ensure compliance with relevant laws and regulations. The other options, such as security controls automation, defined security metrics, or change management processes, are important components of an information security governance framework, but they are not essential to establish it. References:
* https://www.iso.org/standard/74046.html
* https://www.nistf.gov/cyberframework
* https://www.iso.org/standard/27001

The eradication phase of an incident response plan is where the root cause of the incident is determined and eliminated. This phase involves identifying and removing all traces of the malicious activity from the affected systems and restoring them to a secure state.
References = NIST SP 800-61 Revision 2, CISM Review Manual 15th Edition

The first course of action when one of the organization's critical third-party providers experiences a data breach is to invoke the incident response plan, which means activating the incident response team and following the predefined procedures and protocols to respond to the breach. Invoking the incident response plan helps to coordinate the communication and collaboration with the third-party provider, assess the scope and impact of the breach, contain and eradicate the threat, recover the affected systems and data, and report and disclose the incident to the relevant stakeholders and authorities.
References = Cybersecurity Incident Response Exercise Guidance - ISACA, Plan for third-party cybersecurity incident management