According to federal regulations, what must an investigator do to classify individuals as human subjects?

To classify individuals as human subjects according to federal regulations, an investigator must obtain, use, or study identifiable private information about those individuals. The definition of a human subject in research is explicitly linked to the collection and analysis of data that can identify an individual, especially in situations where the information collected can bridge the gap between the data and identifiable personal characteristics.

When researchers engage in studies that involve identifiable private information, they must consider the ethical implications and adhere to established guidelines for protecting participants' rights and welfare. This includes obtaining informed consent, ensuring confidentiality, and addressing any potential risks to the subjects involved in the research.

The other options do not align with the regulatory requirements for defining human subjects. Analyzing public behavior does not meet the threshold for identifying individuals, as it generally pertains to observations that do not involve private information. Surveying participants anonymously will not qualify them as human subjects, since anonymity ensures that individuals cannot be identified. Conducting experiments without consent violates ethical standards and regulatory guidelines, thus cannot classify those involved as human subjects legitimately.