单项选择题

What are not the shortcomings of Students of United States history seeking to identify the circumstances that encouraged the emergence of feminist movements

A.they have analyzed less fully the development of specifically feminist ideas and activities
B.the ideological origins of feminism in the United States have been obscured
C.they failed to recognize that feminism was then a truly international movement actually centered in Europe.
D.they have thoroughly investigated the mid-nineteenth-century American economic and social conditions