Godinez: In the past, land was sometimes measured by the amount of time required to plow it.
Conclusion
It became necessary to adopt new measures of land (beyond "plow time") when land uses diversified.
Evidence
The initial convention for measuring land was "plow time". But knowing how long it takes to plow a piece of land doesn't tell you how many apartment complexes could be built on that parcel.
Evaluate
For years and years, LSAC avoided putting the conclusion in the final sentence on Main Conclusion questions (too obvious a place to look for it). But recently it's become more common, mostly as a way of trolling test prep advice.
There are three keywords we might lean on here: thus, however, therefore.
The first "Thus" is an implication being drawn of the "plow time" method. We used standard X. Thus, according to standard X, this thing would be different from that thing.
Although "thus" is usually indicating a conclusion the author is drawing, it can also be used to designate cause/effect relationships, or in this case, rule/implication relationships.
"However" usually means that we are leaving background ideas and entering the Author's argument, but we still have to figure out whether the author's argument will go Support, then Conclusion or go Conclusion, then Support.
The "Therefore" tells us that this argument is going Support, then Conclusion.
We can always test whether we've found the right claim as the conclusion by asking, "Why should I believe that?" and making sure that there's a supporting idea provided.
Why should we believe that as land uses diversified, we needed to adopt new measure of land?
Because, the old measure (plow time) wouldn't tell someone how many acres a given plot of land was, if they wanted to build apartment complexes on it.
Goal
Just pick the answer that is closest in meaning to the final sentence, which was the Conclusion.