详解
Choice B is the best answer. In the first sentence of the passage, Smith introduces the argument that slavery is a "political question" and therefore not "within the 'province of woman.'" In the second sentence, Smith voices her opposition to this argument: "It is not true that [slavery] is merely a political question, it is likewise a question of justice, of humanity, of morality, of religion." In other words, slavery is too broad a problem to be classified solely as "political," in Smith's view. However, in the fourth paragraph, Smith returns to the political aspect of the argument at hand by addressing how women must engage in the subject of slavery on a political scale. She argues that "admitting [slavery] to be a political question" doesn't mean that women have "no interest in the welfare of our country," as women must criticize slavery and its "unjust laws" and seek to stop the nation's "downward course" by choosing to not "remain inactive." Therefore, Smith develops her argument about slavery as a "political question" over the course of the passage by dismissing the designation as too narrow but then demonstrates its relevance to her audience.
Choice A is incorrect. Although Smith does offer alternative ways of defining the problem of slavery, she doesn't claim that the designation of slavery as a "political question" is outdated, but rather that it is insufficient. Choice C is incorrect because Smith doesn't contend that the designation of slavery as a "political question" has become trite, nor does she invite her audience to revitalize it. Choice D is incorrect. Although Smith's argument is intertwined with questions of gender roles, she doesn't describe the meaning the designation of a "political question" has for men and then challenge women to embrace it.