Pre industrial Age, What did people use to store or broadcast information?​

Rank the following from most to least devasting: ordovician, permaian, cretaceous, pleistocene

According to ohrp, a problem is an “unanticipated problem” when it meets which of the following criteria: unexpected, related or possibly related to the research, suggests that the research does not put the subjects or others at greater riskunexpected, related or possible related to the research, suggests the research puts subjects or others at greater riskunexpected, unrelated to the research but still occurring with a subject, suggests the research puts others at greater riskexpected, related or possible related to the research, suggests the research puts others at greater risk

Chen's research team randomly assigned some newborns and their mothers either to a breastfeeding promotion group (where breastfeeding was encouraged, but not required) or to a normal pediatric care group (where breastfeeding was neither encouraged nor discouraged). which research method did they use?