According to the federal regulations, which of the following studies meets the definition of research with human subjects?
A. A researcher uses the Customs Office's passenger lists for ships bringing immigrants to the US between 1820-1845 to track the numbers of immigrants from certain ethnic groups.
B. A researcher conducts a linguistic study of comments posted on a local public blog.
C. A developmental psychologist videotapes interactions between groups of toddlers and their care givers to determine which intervention methods most effectively manage aggression.
D. 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.
Answer: C.