What must contribute to the strength of Ancient Chinese dynasties a they maintained good farmland by managing the rivers
b they kept outside Invaders from crossing the Himalayas
c they protected grassland so that they stayed Green for herding
d they guarded the sea so that Outsiders cannot invade the coasts

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.