详解
Choice C is the best answer. In the last sentence of the third paragraph, Smith argues that the threat of a war precipitated by slavery "is of itself sufficient to arouse the slumbering energies of woman" to speak out against slavery's injustice. In other words, women have the potential to protest slavery, but they have been relatively inactive, or dormant, up until now. Therefore, the word "slumbering," as used in this sentence, most nearly means dormant.
Choices A, B, and D are incorrect because in the context of the passage, "slumbering" means dormant, not lethargic (choice A), drowsy (choice B), or unconscious (choice D).