Question 125·Medium·Inferences
Entomologist Faye Rinaldi and colleagues surveyed lady beetles (ladybugs) in a dense urban district, sampling both street-level parks and rooftop gardens atop buildings 10 to 20 stories high. The team identified many of the same lady beetle species in both settings. To account for this overlap, the researchers proposed two possibilities: warm updrafts along building facades may lift beetles from parks to rooftops, and rooftop gardens planted with similar vegetation may serve as sources from which beetles regularly fly down to street level in search of prey. Either explanation suggests that ______
Which choice most logically completes the text?
For “most logically completes the text” questions, first read the entire passage around the blank so you understand the setup and the logical role of the missing piece (here, a conclusion that follows from either of two explanations). Identify what both explanations or statements have in common, then look for the answer that restates that shared idea in a general way without adding new details. Eliminate any choice that introduces topics, comparisons, or causes the passage never mentions, even if they sound scientifically plausible, and choose the option that is supported by the given information alone.
Hints
Use the structure around the blank
Focus on the words just before the blank: “Either explanation suggests that ____.” What kind of statement must fit after that phrase so that it makes sense with both explanations?
Compare the two proposed possibilities
Reread the two explanations the researchers give. Ask yourself: what do these two different mechanisms have in common? They are both offered to account for the overlap in species between the two settings.
Beware of extra, unsupported ideas
Look at each answer choice and ask: does the passage actually talk about this? Be especially cautious with choices that mention numbers of species, causes of population growth, or differences in diet—are any of those topics discussed in the text?
Step-by-step Explanation
Understand what the blank must do
The question asks, “Either explanation suggests that ____.” That means the correct completion must be a general conclusion that would follow from both of the researchers’ proposed explanations, not just from one of them and not from information that isn’t given.
Break down the first explanation
The first explanation says that warm updrafts along building facades may lift beetles from parks to rooftops.
This implies a path where beetles at street-level parks can be carried upward to rooftop gardens. Notice there is nothing here about numbers of species, population growth, or what the beetles eat—only a way they could get from one place to another.
Break down the second explanation
The second explanation says that rooftop gardens planted with similar vegetation may serve as sources from which beetles regularly fly down to street level in search of prey.
This implies beetles starting in rooftop gardens and flying down to street-level parks. Again, the focus is on a route between the two settings, not on having more species, causing population growth, or feeding on different prey.
So both explanations describe beetles going from one habitat to the other, just in opposite directions.
Match that shared idea to the answer choices
Now test the choices:
- Choice B claims rooftop gardens host more species than parks. The passage only says many of the same species appear in both, not that one has more.
- Choice C talks about population growth, which the passage never mentions.
- Choice D says beetles on rooftops feed on different prey, but the text doesn’t compare diets.
- Choice A states that lady beetles move between rooftop gardens and street-level parks, which is exactly the shared idea implied by both explanations (updrafts moving them up, and beetles flying down).
Therefore, the correct answer is A) lady beetles move between rooftop gardens and street-level parks.