Which of the following studies meets the definition of research involving human subjects?

The selection involving videotaping toddler interactions to observe aggression management meets the definition of research involving human subjects because it directly engages participants who are identifiable individuals (toddlers in this case) and observes their behavior in a systematic way. This research involves collecting data through interaction and observation of living individuals, which is integral to defining human subjects research.

For research to be categorized as involving human subjects, it must involve a living individual from whom data is collected through intervention or interaction or whose private information is obtained. This underscores the ethical considerations in protecting the rights and welfare of those individuals being studied. In this scenario, there is a clear focus on behaviors specific to the participants and a structured approach to observing and understanding those behaviors.

The other options do not fit this definition because they either involve data that is no longer current (such as historical passenger lists), anonymous or publicly available information that does not identify living individuals (like comments on a blog), or involve a subject matter (like a survey of patients) that might not provide enough direct interaction or intervention to meet the criteria for human subjects research unless specific identifiers are included. Hence, the option involving videotaping toddler interactions aligns with the essential elements of engaging human subjects in research.