Which of the following is the BEST course of action when confidential information is inadvertently...

Declaring an incident is the best course of action when confidential information is inadvertently disseminated outside the organization, as it triggers the incident response process, which aims to contain, analyze, eradicate, recover, and learn from the incident. Declaring an incident also helps to communicate the exposure to the relevant stakeholders, such as senior management, legal authorities, customers, or regulators, and to comply with the applicable laws and regulations regarding notification and disclosure. Changing the encryption keys, reviewing compliance requirements, or communicating the exposure are possible steps within the incident response process, but they are not the first course of action.

References = CISM Review Manual 2022, page 3121; CISM Exam Content Outline, Domain 4, Task 4.12; CISM 2020: Incident Management; How to Respond to a Data Breach