Which Statement Is Most Valid Concerning the Effects of Maternal

Which statement is most valid concerning the effects of maternal employment?

A) Children of employed mothers have lower scores on math and reading tests than do children of full-time homemakers.
B) Negative effects of maternal employment during the first year of an infant's life have been demonstrated in wide-ranging studies across groups of different socioeconomic classes.
C) Research does not support the idea that maternal employment per se has negative effects on children's development.
D) Working mothers actually spend more time with their children than do nonworking mothers.