Numerous Ancient Mayan cities have been discovered in the

Numerous Mayan cities have been discovered.
The ruins lack any evidence of destruction by invading forces, internal revolts, or disease and appear simply to have been abandoned.

Theory: cities were abandoned due to a severe drought known to have occurred in the region between 800 and 1000 AD

Now, the premises do not tell us when the cities were abandoned. To theorise that they were abandoned because of the draught, first we need to establish that they were abandoned during that period. Then, that the draught and the abandonment are related.

A. Ample archaeological evidence of Mayan Peasant revolts and city-state warfare exists, but such events could never result in the permanent abandonment of cities.

This option rules out "local revolts by a specific group" as the cause. A very weak supporter, if at all.
Further, the premises talk about "no destruction from invading forces, internal revolts .. etc". This option says that there is archaeological evidence of peasant revolt (perhaps in the form of drawings etc). Hence, the option is not inconsistent with the given premises.

B. No monumental inscriptions created after 900 AD have been found in these cities, but inscriptions dating before that time have been found in abundance.

This option tells us that the cities were likely abandoned during the draught. It does provide an important link to our theory. Answer.

C. studies of Yucatan Lake sediment cores provide conclusive evidence that a prolonged drought occurred in the region from 800 to 1000 AD

Whether the draught occurred or not is not under consideration. The premises tell us that it did occur.

D. climatic studies have documented cycles of intermittent drought in the Yucatan peninsula dating from the present to at least 7000 years ago.

Irrelevant. The cycle of draughts doesn't strengthen our conclusion.

E. The Mayan City, Uxmal, was continuously inhabited from 500-1500 AD
Data about one city doesn't establish anything, and even if it does add value, it actually weakens our conclusion.

Answer (B)

VERITAS PREP OFFICIAL SOLUTION:

If you had anticipated a problem or gap in the previous argument before going to the answer choices on this problem, it would not have been “We don’t know if the drought occurred.” The argument specifically tells you that the drought was known to have occurred. However, the argument is lacking one very important piece of information. The argument states that a drought occurred between 800 AD and 1000 AD and concludes that this drought must have caused the disappearance of the Maya. However, absolutely no evidence is given that the Maya actually disappeared during the time of the drought. Answer choice B gives you exactly that missing piece of information and is thus correct. Almost any person who is new to critical reasoning makes the mistake of picking answer choice C on this problem because it seems to be important. Had you considered the argument before moving to answer choices, it is unlikely you would have made this mistake.

B is the answer. C provides evidence of the occurrence of a drought between 800 and 1000 AD. But it cannot be inferred from C that the drought CAUSED the abandonment of the city.
B provides evidence that no monumental inscriptions were found after 900 AD. This increases the likelihood that there was a drought around 900 AD, thus supporting the conclusion. The strengthener just needs to increase the likelihood of the conclusion. That is exactly what B does in this case - increase the likelihood of the conclusion that the supposed drought caused the abandonment of the city.

Hope this helps.

I choose C..Although I am incorrect..But I would like to point out that: In a real GMAT question are there 2 or more strengtheners such that one strengthens more than the other..As per what I have read..such is not the case..It is always 1 strengthener..and other neutrals,weakeners or irrelevants

Experts please vouch for the above

Dear mahendru1992,
I'm happy to respond. Let's look carefully at the last sentence of the prompt:
Some archaeologists have theorized that the cities were abandoned due to a severe drought known to have occurred in the region between 800 and 1000 AD

The statement of causality, drought caused abandonment, is indeed part of the archaeologists' theory, their best guess. That's pure speculation, not fact. By contrast, we are told the "severe drought" itself is "known to have occurred in the region between 800 and 1000 AD." That's not part of the theory. That's agreed-upon scientific fact. Essentially, the archaeologists are saying, "We all know about that drought. We think that drought caused those folks to abandon those cities." The modifier in that last sentence, beginning with the participle "known," informs us very clearly which parts of the sentence are speculation and which are fact.

Choice (C) simply confirms this fact, a fact that was already "known" before we found out about (C).

Does all this make sense?
Mike

Why B is correct?

The cities might be abandoned from other factors during 800 to 1000 AD.

Yes, definitely other factors during 800 to 1000 AD can play their role in the abandonment. But, B makes the conclusion MORE believable, isn't it? Thus, B is a valid strengthener. Remember, a strengthener need not prove truth of the conclusion.

Thanks

Can you explain why C is incorrect, please?

Sure. The conclusion says: Some archaeologists have theorized that the cities were abandoned due to a severe drought known to have occurred in the region between 800 and 1000 AD
Since the drought is already known to have occurred, choice C just repeats the premise.
Thnx.

Hi binit,
Isn't the question says to strengthen the archaeologists thoery ? And Archaeologist's theory clearly says that "Some archaeologists have theorized that the cities were abandoned due to a severe drought known to have occurred in the region between 800 and 1000 AD" So why not C ?

Hi subhamoycomputer

C. Studies of Yucatan Lake sediment cores provide conclusive evidence that a prolonged drought occurred in the region from 800 to 1000 AD.

In other words, C confirms that a prolonged drought occurred in the region. BUT we already knew it, right? The drought was well known. So, C is just the repetition of an info already known. Is that okay?
U can't strengthen by repeating a already known info. So, C is wrong.

U need to add something new that can make the conclusion more believable. So, B is correct.

Pls note, C is a classic wrong answer (strengthener), GMAT always uses to trap test-takers.

Could anyone please explain to me why option A is incorrect?

Dear csaluja,

I'm happy to respond.

My friend, I am going to chide you. This is not a high quality question. Think about the amount of effort you put into writing this question--probably not much. The way education works is that you have to put in your own effort to move forward. Furthermore, if you don't understand (A), what don't you understand? Why doesn't it make sense to you about why (A) is wrong? What do you think it could be correct? If you explain yourself in detail, you make your question clearer to an expert who can answer it, but more importantly, explaining your thought-process helps you to understand the logic of the question more deeply, and that increased understanding would help you assimilate more deeply any answer. See:
Asking Excellent Questions
Here is my challenge to you. First, read this linked blog article. Then, come back to this thread, and study each entry, looking for discussion of (A). Finally, write the highest quality question you can, explaining your thought process thoroughly. If you do all this, I will be more than happy to answer you.

Mike

mikemcgarry I have some doubts regarding this CR.It is mentioned in the argument that "Some archaeologists have theorized that the cities were abandoned due to a severe drought known to have occurred in the region between 800 and 1000 AD"

Option C directly strengthen the "theory by Some Archaeologists" by stating that ''........cores provide conclusive evidence''. D sounds more vague and it has to be further assumed that the monumental inscriptions created after 900 AD will never be found. It will be helpful if you clarify this doubt.

Dear pkm9995109794,

I'm happy to respond.

First, let's look at that sentence from the prompt:
Some archaeologists have theorized that the cities were abandoned due to a severe drought known to have occurred in the region between 800 and 1000 AD.
That's a complicated sentence, because it contains both evidence & conclusion.

The factual, evidence part is the fact that a "severe drought . . . occurred in the region between 800 and 1000 AD." That's a fact, thoroughly know and beyond dispute.

The conclusion, the controversial part, is why these cities were abandoned, when they were abandoned, and whether the drought had anything to do with it. The argument is about that.

Yes, I agree that (C) is a strong statement, but the problem with (C) is that it tells us what we already know. From the prompt, we already had zero doubt about that "severe drought," so (C) simply piles more evidence for what already is certain. That's not particularly helpful.

You mentioned (D), but I think you meant the OA, (B). Another thing I want to make clear is that the GMAT CR arguments are not about proof. They are not about mathematical certainty. Sometimes a strengthener will be very strong and will come close to guaranteeing the argument. Other times, a strengthener simply adds further evidence or another line of support for something.

Think about the archaeologists: these people are academics and they are trying to build a plausible case for a scenario that occurred over a millennium ago. Nothing about archaeology involves proof beyond doubt: it's the very nature of the discipline that there's always a certain amount of uncertainty. We are looking for a story that most plausible, not for something that constitutes watertight proof.

With this mind, consider (B). Up until this point, the archaeologists knew about the drought and were trying to build a case that these ancient cities were abandoned in the 800 - 1000 AD period. Choice (B) provides a completely different category of evidence. "No monumental inscriptions created after 900 AD have been found in these cities, but inscriptions dating before that time have been found in abundance." In terms of archaeology, that's exceptionally strong evidence--lots of inscriptions up to about 900 AD, and they all of sudden, they stop. Wow! A sudden break in the historical record: this certainly would corroborate the story that the archaeologists were trying to build, that the abandonment of the cities was something that happened in a sudden catastrophic way, rather than, say, in a process of gradual attrition.

You said that choice (B) "sounds more vague and it has to be further assumed that the monumental inscriptions created after 900 AD will never be found." Keep in mind that these are inscription on monuments. One of the defining qualities of a monument is its large size--that's precisely why we have the English word "monumental." If we were discussing inscriptions on something small, then it would be conceivable that some would be found and some not found. Instead, we are discussing monuments, which as a general rule are very hard to miss. It sounds as if there are multiple monuments on which there are copious inscriptions from the time before 900 AD and then absolutely none after that point. It's not as if any inscriptions on a monument are going to be hidden: the whole point of inscriptions on monuments is to make them as visible as possible. It's not likely that there would be multiple monuments that the archeologists don't find, and it's not likely that they would miss a large number of inscriptions on any monument they find. Thus, it's not really an "assumption" that later inscriptions will not be found. Any familiarity with the tangible processes here would make this evident.

I am going to guess that you don't have detailed knowledge of archeology. I will recommend that whenever you encounter a GMAT Verbal Practice problem about a topic about which you know little, it can be very good reading practice to read a little more about that topic. Also, for the GMAT CR, it's very important to have some idea about real events in the real world. See:
GMAT Critical Reasoning and Outside Knowledge

Does all this make sense?
Mike

Dear VeritasKarishma DmitryFarber IanStewart VeritasPrepBrian,

Q1. Why is choice A. not correct?

IMO, choice A. eliminates the alternate cause behind the permanent abandonment of Mayan cities.
The permanent abandonment could be from a severe drought as suggested by the argument, or it could be from revolts or warfare. Hence, eliminating the competing cause for the abandonment strengthens the causal relationship in the argument.

Why is this line of think wrong?

Q2. Is choice A. INCONSISTENT with this part of the passage: The ruins LACK any evidence of destruction by invading forces, internal revolts, or disease and appear simply to have been abandoned ?

However, IMO, answer choices should not go against what is given in the passage.

Q3. Considering that choice B. is correct, do we have to assume that:
1) Mayan people tolerated the severe drought for 100 years (from 800 AD to 900 AD). I am not sure why didn't they tolerate for another 100 years?
2) The abandonment is a very abrupt, not gradual, process?
(For example, people gradually moved out of the cities few families a month. The abandonment process could take over many year. Hence, the number of inscriptions should GRADUALLY reduce, not abruptly disappear.)

Please enlighten me

There's an official question with very similar logic to this one, and that question is more deserving of study. C should not be a tempting choice -- restating a premise never adds anything to an argument. Answer A I suppose would be the best choice if answer B were not there, since answer A rules out some alternative causes, but only a couple of them (it doesn't even rule out one mentioned in the stem -- disease), so it doesn't accomplish much.

The archaeologists found an abandoned city. That city might have been abandoned in 1500 AD or 500 AD. To support a hypothesis that it was abandoned because of a drought around 800-1000 AD, we want evidence that the city was abandoned around that time. So B strengthens the argument. It's very tempting, when reading this question, to think you want evidence connecting drought with the Mayans' departure from the city (that's what I was looking at first), but when no answer choice makes that connection, it's important to step back and think about the problem in a different way.