[deleted because poster did not cite source]

sorry..my actual question is, I have a doubt between A and B.

When I see "Has contributed"..i usually think that it is true even now.
But it is necessary..like there may eb a survey in 2006 and that rebutted this fact.

should we give any importance to this...??
please clarify. thanks!!

[deleted because poster did not cite source]

What we're trying to say here is that Mexico has largest number of foreign born residents on a survey. This information isn't crucial to the meaning of the sentence and when the clause is removed, the sentence reads perfectly. Selections C, D, and E are really awkward. Selection A uses the word "for" which is incorrect.
I think the answer is B because it is the only selection that modifies what Mexico accounted for. Although "has contributed" seems passive, it means that it is an ongoing action that started in the past and continues to the present.

I am studying for the GMAT too and could be wrong. What is the correct answer?

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thank you.