单选题 .  ①Much recent work has examined the claim that women encounter increasing obstacles relative to men as they move up the organizational ladder in business. ②This proposition, which we term the increasing-disadvantage model, is a core element of the popular glass ceiling metaphor. ③Despite continued widespread public acceptance of the glass ceiling idea and some consistent findings, most research to date has failed to support the increasing-disadvantage model. ④Indeed, several studies based on private-sector firms find that women's mobility prospects improve, rather than decline, as they climb upward in corporate hierarchies. ⑤In the public sector, researchers have found either no sex differences in mobility or a larger female disadvantage in lower grades.
    ①Comparing cross-sectional national samples of workers, Baxter and Wright found no evidence in the United States, and only limited evidence in Sweden and Australia, that women's probability of being located in a higher versus a lower hierarchical level declined relative to men's at higher levels. ②Taken together, these findings suggest that the glass ceiling may be a myth. ③Women's scarcity in top organizational ranks may simply represent the cumulative effect of a constant-or even decreasing-disadvantage at successive hierarchical levels.5.  The primary purpose of the passage is to ______