How does russia's human capital investment relate to its per capita gdp? a. it has heavy investment and a high per capita gdp. b. it has heavy investment and a limited per capita gdp. c. it has limited investment and a high per capita gdp. d. it has limited investment and a limited per capita gdp.

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?