Which of the following is considered protected health information (PHI)?

Protected Health Information (PHI) refers to any health information that can identify an individual and is related to their health status or health care. This includes a wide range of identifiers that can be used to trace back to the individual, making it sensitive and confidential.

In this context, the Social Security number is considered PHI because it is a unique identifier that can be directly linked to an individual. When combined with health-related data, it could potentially compromise someone's privacy if disclosed improperly. The essence of PHI is not just about health conditions but also about the ability to link that information to a specific person, and the Social Security number plays a crucial role in establishing that connection.

Other options, such as a company name, public domain information, and advertising materials, do not qualify as PHI. A company name reveals no individual health information, while public domain information is accessible to all and lacks confidentiality. Advertising materials typically do not contain identifiable health-related data that pertains to an individual's personal health records. Therefore, these do not meet the criteria for being protected health information.