Who were the undecideds

Using the charts above which of the following matches the people with the set of laws they created

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?

Acurb of this color means you may not stop a) yellow b)green c) red d) blue