Which of the following is NOT considered protected health information?

Protected Health Information (PHI) is any information held by a covered entity that relates to a person's health status, provision of healthcare, or payment for healthcare that can identify the individual. Medical records, billing information, and health insurance information all fall under this definition, as they contain sensitive information directly associated with a person's healthcare and can be used to identify them.

Work history, on the other hand, does not inherently contain health-related information nor is it typically linked to an individual’s medical treatment or status. While it may be relevant in a broader context of employment benefits or workers' compensation cases, work history alone does not disclose any health-related information. Thus, it is not classified as protected health information under the Health Insurance Portability and Accountability Act (HIPAA) and is the correct choice as it is NOT considered PHI.

This distinction highlights the specific focus of PHI on health and healthcare-related data, which is paramount in healthcare privacy and security discussions.