this is very hard.
look at choice A and E.
that clause or similar clause such as "in which" clause of choice D, is used to define a noun. whenever we see this kind of clause, think that there are more than 1 kind of noun, for simplicity, think that there are 2 kinds of noun and one kind of noun is the kind which is defined by "that clause".

so, choice E means there are 2 (in fact more than 1) kinds of ownership, and they return to the kind that had been pre columbian form. this is not logic.

the intended meaning is there is only 1 kind of ownership. in history, there can not be 2 kinds of this ownership. choice E implies that there are many kinds of ownership. this meaning is absurd. choice E is gone.

choice D is wrong for the same reason as choice E is wrong.

touch rule declares that which/that clause should touch to noun modified. but this rule permit us to find the inferiors choice relative to a better choice. this rule is not hard and fast rule by the fact that many OA on og books contain which/that clause which do not touch the noun modifies.

gmat sc is hard because it requires us to be actively to find an error. only when we know this way, we can write. what is "active to find " error.

many times, we understand explanation but can not solve a new problem because we are not active. to be active to find error means we have to have skill.

one skill for problem regarding "that clause" is that

takeaway: whenever we see that clause, we think that there are 2 (more than 1) of the noun, and the sentence says about one kind of the noun which is defined by "that clause"

whenever we see "which" clause, think about cutting off this "which clause". if the remaining sentence after cutting off is good, which clause is correct.

above is example of "active to find error".

Our main focus should be on ‘a return’ . The underlined part should be comparable to this.

Parikshit
The pre-Columbian” era refers to the period in the Americas before the arrival of Columbus in 1492.
Contrary to belief, the Pre Columbian era included various social marvels in the form of architecture, astronomy, and writing systems. The Spanish people who colonized these countries were surprised at the diversity and depth of these cultures. The land ownership pattern that existed in these American countries is one such marvel, which the European invaders respected greatly.
During the agro- evolution, the Zapata group wanted to return to this old system of land ownership as part of the reforms from the then Spanish form of ownership, which had been thrust by the colonizers by brutal military force.
‘To what had been’ refers to the native system that existed in those countries before the Europeans’ colonized them.

I hope the milieu is clear now.
_________________

Why can't we use "that", as used in option E, to refer back to "ownership"?

If this can happen in following example, why can't it happen in above one.

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