Historian: The practice of primogeniture, under which only oldest sons

When a GMAT question asks you for the "best supported" answer choice, you have to find a choice that you can PROVE from the given statements. You'll arrive at this choice by combining two or more statements from the passage with as much logical certainty as possible.
(As an example of what I mean by "combining statements", if a passage were to say "My car fits in parking spot number 12" and "My Wife's car does not fit in parking spot number 12", we could combine these statements to conclude "My Wife's car is bigger than mine in at least one dimension".)

This problem has less rigorous logic than its counterparts on the official exam, and is problematic in that you have to attribute factual accuracy to a statement about what "would have seemed" true in order to arrive at the correct answer——but at least it follows the basic contours of the official problems, by giving just only one answer choice that comes anywhere close to being a logical conclusion of the combination of two or more given statements.

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As you read through the passage, you should look for pairs of statements with an obvious connection that will let you combine them (like the parking spot that's mentioned in both of the statements above).

The two bold statements here have a clear relationship:

The underlined bold sentence says that the oldest son in a family with generational wealth would inherit ALL of that wealth——meaning that the family's other sons (if there were any) would get nothing.

Those non-firstborn sons, who were barred from receiving an inheritance, were the "large population of aristocratic young men lacking any economic resources or prospects at home".

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We can make a further connection by noting that these non-firstborn sons (who were denied an inheritance) are "these men" in the following sentence:

This is where the current problem falls short of a GMAT-worthy degree of logical rigor: This statement——about what "would have seemed" necessary——does not literally tell us that any of those younger sons actually DID take this option and go join Crusades in faraway lands, but we have to assume that significant numbers of them did so.
The GMAT will not do this; i.e., on "prove an answer" problems, you will never have to infer a greater degree of certainty/probability than the words actually say.

But anyways... With that connection made, we have all the building blocks that we can assemble to get choice A as a consequence.


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