Harvey's Research Using the Large National Longitudinal Survey of Youth

Harvey's research using the large National Longitudinal Survey of Youth examined the impact of mothers' working during the first three years of their child's life.The study found that the children of working mothers had __________ the children of nonworking mothers.

A) more behavioral problems than
B) had better cognitive development than
C) both more behavioral problems and better cognitive development than
D) no significant or lasting differences from