Recent Research on the Effect of Maternal Employment on Infants

Recent research on the effect of maternal employment on infants' cognitive development found that

A) infants had lower levels of cognitive development and were less compliant if their mothers worked at all during the babies' first five years.
B) there were no differences, except that teachers rated the children of employed mothers as having higher achievement motivation and fewer internalizing problems.
C) infants of mothers who were employed had lowers levels of cognitive development, were less complaint, and were less securely attached.
D) infants from middle-class families were less social and had lower levels of cognitive development if their mothers worked.