Kim: Some people claim that the battery-powered electric car represents a potential solution to the problem of air pollution.
Conclusion (So)
Even if every gasoline-powered car on the road were replaced by an electric car, the result would at best be an exchange of one source of fossil-fuel pollution for another.
Intermediate Conclusion
Putting more electric cars on the road would require building more generating facilities.
Evidence (Since)
Current generating facilities are operating at maximum capacity.
Recharging batteries takes electricity, and most of our electricity comes from burning polluting fossil fuels.
Evaluate
Older tests have this Main Point variation on Main Conclusion questions. We can approach them fundamentally the same way, but most Main Point questions involve an implicit conclusion, usually a rebuttal conclusion that was never said out loud, or an answer to a rhetorical question that was posed.
This definitely starts off like we're headed to Rebuttalsville, USA. We get an Attribution that . From just that moment, we'd already start suspecting that our author's implicit conclusion is going to be , and then we'd anticipate a Pivot + Pushback.
The word "But" signals that Kim is about to push back, and everything after it builds the rebuttal. Recharging runs on electricity, electricity comes mostly from fossil fuels, and more electric cars would mean more fossil-fuel plants. The final sentence, indicated by "So," is where all of that lands: swapping gas cars for electric cars just moves the pollution from tailpipes to power plants.
The last sentence does seem to work as an explicit conclusion, and it's more or less a restatement of our prediction, that electric cars won't solve the pollution problem.
Goal
Look for a paraphrase of the final sentence, or one shooting down the initial attribution, like .