Why did the community near Wolf Creek Pass in Colorado petition the government? To ask for new rules surrounding water processing
To draw attention to the challenges of the polar bear
To improve safety of the highway and add crossing signs
To remove a developer's permit to construct a resort

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?