According to United States census data, while there was about one-third of mothers with young children working outside the home in 1975, in 2000, almost two-thirds of those mothers were employed outside the home.
(A) while there was about one-third of mothers with young children working outside the home in 1975, in 2000, almost two-thirds of those mothers were employed outside the home
- SV issue. "was" doesn't agree with plural subject "one-third of mothers"
- Seems as if children were working outside.
- "those mothers" refers to the same mothers which is wrong.
(B) there were about one-third of mothers with young children who worked outside the home in 1975; in 2000, almost two-thirds of those mothers were employed outside the home
- "who" refers to children which is wrong
- "those mothers" wrong.
(C) in 1975 about one-third of mothers with young children worked outside the home; in 2000, almost two-thirds of such mothers were employed outside the home - ok
(D) even though in 1975 there were about one-third of mothers with young children who worked outside the home, almost two-thirds of such mothers were employed outside the home in 2000
- "who" refers to children which is wrong
(E) with about one-third of mothers with young children working outside the home in 1975, almost two-thirds of such mothers were employed outside the home in 2000
- "with" means that the first "one-third of mothers with young children working outside the home in 1975" and second "two-thirds of such mothers were employed outside the home in 2000" happened at the same time which is wrong.