Question 243·Hard·Transitions
Atmospheric scientists have long known that volcanic eruptions can cool the planet by spewing sun-blocking aerosols high into the stratosphere. ______ policymakers have begun exploring whether an engineered version of this process, called stratospheric aerosol injection, could be deployed to mitigate global warming.
Which choice completes the text with the most logical transition?
For transition questions, first cover the answer choices and read the sentences before and after the blank, then briefly describe in your own words how the ideas relate: are they agreeing, contrasting, giving an example, showing cause and effect, or just occurring at the same time? Next, label each answer choice by its usual function (contrast, example, addition, cause-and-effect, time, etc.) and eliminate any that do not match your description of the relationship. Only then look at which remaining option fits both the meaning and the sentence’s punctuation and grammar.
Hints
Clarify what each sentence is saying
First, restate each sentence in your own words: What do scientists know in the first sentence, and what are policymakers doing in the second?
Think about how the two ideas connect
Ask yourself: Does the second sentence disagree with the first, give an example of something in the first, or describe an action people are taking because of the information in the first?
Use the typical functions of transitions
Recall: "However" usually shows contrast, "For instance" usually introduces an example, and "Meanwhile" usually shows things happening at the same time. Decide which of these types (if any) fits the connection between the two sentences.
Step-by-step Explanation
Understand the first sentence
Paraphrase the first sentence: scientists already know that volcanic eruptions can cool the planet because they send sun-blocking particles high into the atmosphere.
So, we have a scientific fact about a natural cooling process.
Understand the second sentence
Paraphrase the second sentence: policymakers are now considering whether a human-made version of this same process (stratospheric aerosol injection) could be used to reduce global warming.
This sentence shows what people (policymakers) are doing in response to the scientific fact described earlier.
Identify the relationship between the two ideas
Ask: How does the second idea relate to the first?
- The first idea: a natural process (volcanic eruptions) cools the planet.
- The second idea: people are exploring copying that process to solve a similar problem (global warming).
The second sentence is motivated by or based on the information in the first; it is not opposing it, just an example of it, or something separate happening at the same time.
Match the relationship to the transition choice
Now check each option:
- "However," signals contrast or opposition. The second sentence does not contradict the first.
- "For instance," introduces an example of something just mentioned. Policymakers exploring an engineered process are not an example of a volcanic eruption.
- "Meanwhile," signals two things happening at the same time but not necessarily as a direct consequence. Here, the second sentence is directly connected to the first, not just coincident.
The only option that correctly shows that the second sentence follows from the first as a consequence is "Therefore,", so that is the best choice.