Choice D is the best answer. The author suggests in lines 19-22("meeting... who") that space mining may meet "earthly demands for precious metals, such as platinum and gold, and the rare earth elements vital for personal electronics." In this sentence, "earthly demands" suggests that people want, or desire, these precious metals and rare earth elements.
Choices A, B, and C are incorrect because in this context "demands" does not mean offers, claims, or inquiries.