Taxpayer: For the last ten years, Metro City’s bridge-maintenance budget of $1 million annually has been a prime example of fiscal irresponsibility.
Conclusion
The $1 million / year bridge-maintenance budget has been a prime example of fiscal responsibility.
Evidence
In a well-run program, they'd spend $15 million a year on maintenance, which would limit deterioration and thus limit money they'd need to reconstruct the bridge to $10 million.
Instead, because Metro City has only been paying $1 million / year for the last ten years, they now need to do some emergency reconstruction of bridges that will cost $400 million.
Evaluate
Whenever we're doing a Main Conclusion question, we prime our brain (before reading the paragraph) by reminding ourselves that on Main Conclusion we usually find the conclusion either - in the first sentence, or - as some form of Rebuttal statement
That way, as we read this first sentence, we're listening to it like it might be the Conclusion. We're reading it thinking,
In this case, yes! The first sentence has the very opinionated claim: a prime example of fiscal irresponsibility.
Does the rest of the paragraph try to convince us that the maintenance budget is an example of fiscal irresponsibility?
Yes. It says,
The idea is that if you spend $15 million a year, then you only have to do about $10 million in repairs. Over ten years that would be $150 + 10 million, or $160 million.
Instead, they tried to cheap-out (economize), and they've only spent $1 million per year, and now they have a repair bill of $400 million. Over ten years, that's $10 + 400 million, or $410 million.
Goal
Once we find the conclusion on Main Conclusion, we've done the hard part. Picking our answer just means finding the closest match to whichever claim we determined was the conclusion.
So let's look for an answer that means the same thing as: for the last 10 years, MC's bridge maintenance budget has been fiscally irresponsible.