The conclusion of the argument is that a single, apparently insignificant, departure from safety standards can have severe consequences. Here's how the editorial author reaches this conclusion:

• Northtown Council recently constructed an equipment-storage building that met safety codes in every particular...
• ...except that nails used for attaching roof supports were smaller than codes specify.
• After this one, apparently insignificant departure from safety standards, the equipment-storage building's roof collapsed under the weight of heavy snowfall.
• Therefore, the author concludes that even a single, apparently insignificant departure from safety standards (like using nails that are too small) can have severe consequences (like the roof of a building collapsing).

We're looking for an answer choice that backs up the case of this equipment-storage building. A good choice will provide more evidence that departing from safety standards leads to severe consequences. A good choice could also rule out alternate explanations for the collapse of this equipment-storage building's roof.


Choice (A) tells us that other roofs collapsed during last week's snowfall. Choice (A) also tells us that the standards followed to construct the other roofs were less exacting (i.e., less strict or demanding) than the standards set by today's safety codes. Consequently, (A) confirms that other buildings constructed with a lack of care for safety standards ended up suffering severe consequences.

Even better, this choice tells us that these were the only other buildings whose roofs collapsed from the weight of last week's snowfall. That reduces the likelihood that there are alternate explanations for this damage:

• If (A) were not true, then perhaps the roofs of several buildings that met local building-safety codes in EVERY way also collapsed.
• That evidence would suggest that the roof of the equipment-storage building may have collapsed even if the nails were up to code.
• In that case, the problem would not have been simply a "single departure from safety standards" (the nails).
• Instead, the problem would have been that the safety standards were not strict enough to protect against such a heavy snowfall--even roofs of buildings that met the standards collapsed.

But (A) tells us that this was not the case and thus strengthens the argument.

I hope this helps!