LSAT PT24, S3 Logical Reasoning, Q23, Historians of North American architecture who have …

Why is (B) the answer?

The argument is basically that narrow floorboards were used to "proclaim the owner's wealth." But if narrow floorboards cost the same as wide floorboards to cover the same amount of area, this argument would fall apart.

Although (B) doesn't confirm a narrow floorboard costs more than a wide floorboard, we don't necessarily need that to add support. Imagine if a single narrow floorboard covered 50% of the area of a single wide floorboard but was only 10% cheaper (instead of 50%). That would mean even though narrow floorboards are technically cheaper on a per unit basis, they're still more expensive to use (e.g. to cover 100 square feet of a house).

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