For almost five thousand years after its beginning 2.5 million years

Can somebody tell me whats wrong with B? I mean gramatically.

E

(A) it =? vague referent
(B)(C) Homo habilis began? (X)
(D) "the" needed before "five thousand years"
(E) OK

Is the intended meaning not changing in E
B says 'for almost five thousand years' while E says 'over five thousand years'

Definitely changes the meaning.... such change is not expected to be seen in a real GMAT question.

E is not saying "over 5000 years" (>5000).

It is saying: Over a period of five thousand years...means "during these 5000 years".

Hope my understanding is correct.

Yes sukanyar, you are correct ..
Over a period of five thosand years MEANS during 5000 years

Just to clarify, "changes the meaning" is not a valid reason to eliminate an answer choice. It is common for the answer choices to present different meanings. Our job is to select an answer choice that conveys a clear meaning without committing any grammar errors. We may have to compare several choices to divine the intended meaning, but A is not special or privileged in any way; the correct answer can have a different meaning from that conveyed in A. In fact, since the meaning in A will often be flawed in some way, a change in meaning is often necessary.

In any case, as folks above have clarified, "over a period of five thousand years" really means the same thing as "for five thousand years."

Having said all that . . . this problem is invalid. "Their" has no antecedent, as there is no plural noun in the sentence (Homo habilis is the name of a species, which is singular). Furthermore, "shared their economy" doesn't have a clear meaning in English. Sorry to rain on the parade . . .

Official Explanation

Correct Answer: E

The best answer is E. Choice E is precise and idiomatically phrased. Choice A is illogical because it refers grammatically to Homo habilis. Choice B is less clear and direct.

I don't understand what's the problem with D?

Can someone please explain.

Posted from my mobile device

What is the problem with B, I am unable to understand

Yes. can someone please explain why D is wrong.

Hello thakurarun85,

We hope this finds you well.

To answer your question, Option D incorrectly modifies "five thousand years" with "a period beginning 2.5 million years ago,", illogically implying that "five thousand years" is one specific period of time that began 2.5 million years ago.

We hope this helps.
All the best!
Experts' Global Team

Hello rsrighosh,

We hope this finds you well.

To answer your query, Option B incorrectly uses "Beginning 2.5 million years ago..." to modify "Homo habilis", illogically implying that Homo Habilis began 2.5 million years ago; the intended meaning is that the period of time wherein Homo Habilis roamed the Earth began 2.5 million years ago.

We hope this helps.
All the best!
Experts' Global Team

It says

During five thousand years, a period beginning 2.5 million years ago,

Which means "five thousand years" was the period starting 2.5 mn ago.

I don't see anything wrong in this.

Pleas help.

Hello thakurarun85,

We hope this finds you well.

The construction "During five thousand years, a period beginning 2.5 million years ago" makes it sound as if "five thousand years" is a fixed period of time along the lines of "the Paleolithic Era", which is not the intended meaning.

We hope this helps.
All the best!
Experts' Global Team

What is the intended meaning?

Hello thakurarun85,

We hope this finds you well.

The intended meaning is that Homo habilis began roaming the earth, etc., 2.5 million years ago, and did so for five thousand years.

Option D incorrectly implies that "five thousand years" is a specific period of time, along the lines of "the 21st century"

We hope this helps.
All the best!
Experts' Global Team