thangvietnam
NishaTG
I think it can't be D because if you remove the words "as many as" you can see that "3.6 billion people reside in all the other areas of the world combined" makes sense but "3.6 billion people the residents of all the other areas of the world combined" doesn't make sense.
not understand why d is wrong
pls, explain more
Dear
thangvietnam,
I'm happy to respond.

You and many others on this thread have asked about this.
This is not the highest quality SC question. Veritas usually writes high quality questions, but this one is shakier.
You see, on a true GMAT SC question, there is one right answer, and each of the four incorrect answers are wrong for some unambiguously obvious reason. Even the tempting wrong answers on the GMAT are clearly wrong.
On this problem, that is not the case. In this question, both
(D) and
(E) are grammatically correct.
(E) is shorter, more elegant, so it is better answer, but I entirely agree that
(D) is not "wrong enough" --- in this way, this SC question falls short of the high standards of the GMAT. Also, the "
equal/equivalent" thing does not strike me as particularly GMAT like.
Now, here's the really important thing for you to appreciate. Focusing on the aspects of any question that are not GMAT like will in no way prepare you for the GMAT. This question is one that has fallen short of the GMAT standards, because as an incorrect answer, (D) is not "wrong enough," not as discernibly wrong as an incorrect choice would be on the GMAT. This is the non-GMAT-like part of this question. Focusing on this will not help you at all.
The OA of this question is an incredibly elegant and well-written sentence: it's very much work understanding that. It is certainly worthwhile understanding the parallelism necessary for a well-constructed comparison. Don't be troubled by the aspects of a flawed question that are not GMAT-like.
Do not naively assume that every company that puts something out and calls it a "practice GMAT SC question" has automatically ensured that the quality of the question is up to the GMAT's lofty standards. It is VERY VERY hard to write questions that are as rigorous as those of the GMAT itself, and many companies regularly fall short. Even a very good company, such as Veritas, doesn't hit the mark every time. It's important to appreciate how hard it is to write a question that conforms to these standards, and to be correspondingly suspicious of the quality of each new question you encounter. You can't afford to be naive as a GMAT aspirant, just as you can't afford to be naive in the business world.
Here's a high quality question:
https://gmat.magoosh.com/questions/3284Does all this make sense?
Mike