According to a 1975 U. S. law titled the Education of All Handicapped Children Act, students with special needs must be educated:

When zhang qin went to explore west, he brought back stories of

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?

17 points! ! (explain your answer)