According to the federal regulations, which of the following studies meets the definition of research with human subjects?
A researcher conducts a linguistic study of comments posted on a local public blog.
A developmental psychologist videotapes interactions between groups of toddlers and their caregivers to determine which intervention methods most effectively manage aggression.
A researcher asks the director of a local free clinic about the number of patients in the last two years with newly diagnosed HIV/AIDS.
A researcher uses the Customs Office's passenger lists for ships bringing immigrants to the U.S. between 1820-1845 to track the numbers of immigrants from certain ethnic groups.