OG详解-OG9 文法 Q13

Choice B is the best answer. The sentence explains an advantage of microprobes, noting that because microprobes weigh as little as 50 milligrams, they can explore areas inaccessible to rovers.
Choice A is incorrect. The sentence indicates that rovers can land successfully on Mars despite their weight; it doesn’t explain an advantage of microprobes. Choice C is incorrect. While the sentence mentions that microprobes have been proposed as an alternative to rovers, it doesn’t explain an advantage of microprobes. Choice D is incorrect. The sentence emphasizes a similarity between microprobes and rovers; it doesn’t explain an advantage of microprobes.