According to a recent study by Rutgers University, the number of women in state legislatures has grown in every election since 1968.
(A) the number of women in state legislatures has grown
(B) the number of women who are in state legislatures have grown
(C) there has been growth in the number of women in state legislatures
(D) a growing number of women have been in state legislatures
(E) women have been growing in number in state legislatures
In D, a... number of women means a group of women, whereas the... number of women refers to an exact figure; the illogical suggestion is that a group of women has already been in place in every election, rather than that their total has grown as a result of each election。
Choice E may be faulted for the awkwardness of in number in state legislatures in every election, as well as for weakening clarity by separating the modifying phrase in state legislatures from women.