In the context of federal regulations, human subjects are defined as:

The definition of human subjects in the context of federal regulations is focused on living individuals from whom an investigator gathers data, specifically through interaction, intervention, or collection of identifiable private information. This definition emphasizes the necessity for ethical considerations and the protection of these individuals' rights and welfare in research settings.

The correct answer highlights that human subjects include not just those participating in direct interaction or intervention but also those whose private information can be identified. This encompasses a broad range of research methods, ensuring that all forms of data collection involving living individuals are captured under human subjects regulations, reflecting the need for comprehensive ethical standards in research with potentially vulnerable populations.

This understanding is crucial for complying with regulations and ensuring the ethical handling of research practices, particularly when working with groups that may have specific vulnerabilities, such as prisoners, who require additional protections under the law. The focus on living individuals distinguishes the definition from considerations about deceased individuals, which are governed by different ethical parameters.