What type of research activity with children qualifies for an exemption under Category 2?

The correct answer pertains to research about aptitude testing which qualifies for an exemption under Category 2. This category generally includes educational research involving minimal risk to participants and covers studies conducted in educational settings that focus on individual or group assessments, such as aptitude tests, without revealing personally identifiable information.

Aptitude testing is designed to measure skill or ability, and this type of research is often deemed to pose minimal risk to children. It typically does not involve physical interventions or personal distress and is more about understanding cognitive abilities in a structured, academically relevant way.

In contrast, the other options involve aspects that might not meet the conditions necessary for a Category 2 exemption. For instance, therapeutic interventions usually involve more significant risks and ethical considerations, parental consent is a requirement for most studies involving children regardless of exemption categories, and observing playground interactions may delve into social behaviors that can vary widely and may have greater ethical implications, thus typically not qualifying for the same exemption. Therefore, the nature of aptitude testing research aligns well with the parameters set for exemption under Category 2.