Complex sentence: Third-wave feminism refers to several diverse strains of feminist activity and study, whose exact boundaries in the history of feminism are a subject of debate, but are generally marked as beginning in the early 1990s and continuing to the present.
Split into simpler sentences: Third-wave feminism encompasses several diverse strains of feminist activity and study. Though exact boundaries are a subject of debate, it is generally marked as beginning in the early 1990s and continuing to the present.