Engineer: Wide roads free of obstructions have been shown to encourage drivers to take more risks.
Conclusion (Implied, Likewise)
Blocking out some of the sun to slow or reverse global warming is analogous to making wide roads free of obstructions to reduce accidents.
Evidence
With wide, unobstructed roads, drivers feel like they can take more risks, so the expected uptick in driving safety is somewhat offset by this riskier driving.
With blocking out some of the sun's rays to cool the earth, people/corporations would feel like they can emit more CO2, so the expected cooling effect is somewhat offset by higher emissions.
Evaluate
It's a stretch to call this an argument, as the question stem does. And it's a stretch to call this a Necessary Assumption question as our tagging does.
But when we're given an argument and asked which principle in the answer choices best conforms to that argument, it's similar to being asked, , which is the gist of a Necessary Assumption question.
There are a handful of Necessary Assumption questions on the last 20 LSATs that are really analogies. Most of them still have identifiable conclusions, but some don't. In either case, we want to focus on thinking about the intended analogy.
Analogies are two different sets of specifics, which share some general trait / relationship / truism.
The correct answer to these will feel like it's speaking to something that is true in both cases.
Goal
We want something like, "Attempts to improve X can backfire".