The population of India has been steadily increasing for decades, and it will probably have what is estimated as 1.6 billion people by 2050 and surpass China as the world's most populous nation.

(A) it will probably have what is estimated as
(B) they are likely to have
(C) the country will probably have
(D) there will probably be
(E) there will be an estimated

answer choice C here as well. A is so wrong it's not even funny ;]

The answer is def C. I saw this EXACT question in the GMAT prep software.

C is the best.

D & E out as sentence starting with there are not prefered in GMAT.
A Estimated as is not the correct idiom
B they ---pronoun mismatch

Strongly support for C.

"The country" is necessary due to the appearance of the phrase "the world’s most populous nation" at the end of the sentence

we need subject for "surpass" , so, E and D are gone because there is no such subject.
in B, "they" has no antecedent. gone.
gmat also test logic. in a choice if there is no grammatical mistake, we find logic mistake. logic mistake is so simple that we do not think gmat test this kind of error. but logic test is critical because we need to write logic sentence.
in A, "it" refer to " population". "population' can not have 1.6 bilion logically. we say " population is 1.6 bilion". A is gone.

The population of India has been steadily increasing for decades, and it will probably have what is estimated as 1.6 billion people by 2050 and surpass China as the world’s most populous nation.

A. it will probably have what is estimated as - is redundant (there's no reason to use both "probably" and "estimated"). additionally, "what is" doesn't make any sense.
B. they are likely to have - Pronoun they does not have plural antecedent here
C. the country will probably have - Correct
D. there will probably be - there is no actual indication that the 1.6 billion people will be in india. those choices just say "there will be", which is an idiomatic expression that doesn't indicate a place.
E. there will be an estimated - same as D

Answer C

takeaway: "there is/are" / "there was/were" / "there will be" / etc. DOES NOT INDICATE A PHYSICAL LOCATION. unlike most other uses of "there", in which "there" actually stands for some place, this "there" doesn't stand for anything.

if you want to use "there is" in reference to a particular location, you have to state the location, explicitly, elsewhere in the sentence.
ex: there are three cars in the driveway.
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