Thanks for the question! Here, equally reliable just means that we can depend on them as much for accurate estimations of populations of stable cities. This is what the prompt tells us in the second sentence—they are pretty close with the two stable population cities, but vary more on the third city which was growing rapidly. We can thus conclude they’re equally reliable. Note that technically, in some strict sense, “equally†may be a strong word, but when compared to the other answer choices here, (D) is definitely the best answer. Hope this helps! Feel free to ask any other questions you might have.
