Which choice best describes the relationship between the two passages?

Choice A is the best answer. Passage 1 mainly focuses on describing the National Radio Quiet Zone in general terms: “no electronic transmitters at all,” “a 13,000 square mile stretch of land” intended to “protect two government radio telescopes from human-made interference,” “a rogue radio signal could prevent potential discoveries.” Passage 2 mainly focuses on describing one particular threat to the zone’s integrity: the “lawnbot” that “transmit[s] at the same wavelength as interstellar molecules astronomers study to understand how stars form.” Choice B is incorrect because Passage 1 is only incidentally about Green Bank (as it just happens to be “smack in the center of the National Radio Quiet Zone”) and because describing the National Radio Quiet Zone in general terms is better considered the main focus of Passage 1, not Passage 2. Choice C is incorrect because the drawbacks of the National Radio Quiet Zone are not the main focus of Passage 1 (the author refers to the restriction as “necessary,” for example) and because the benefits of the zone are not the main focus of Passage 2. Choice D is incorrect because neither passage focuses mainly on either praising or criticizing astronomers.