In an experiment, researchers played a series of musical intervals

EXPLANATION FROM POWER SCORE

Hmm. The evidence is, “Babies pay more attention to perfect octaves,” and, “Perfect octaves are prevalent in music around the world.” The conclusion is, “Therefore humans have a biological predisposition to pay more attention to perfect octaves.”

This seems fairly reasonable I suppose, but if I were the opposing attorney I would hammer on the “biological disposition” part. How do we know babies didn’t learn to pay attention to perfect octaves from their parents? What came first: the chicken or the egg? Isn’t it possible, since perfect octaves are prevalent around the world, that babies immediately start to be indoctrinated with perfect octaves as soon as they’re born (nay, while they are in the womb!), and therefore tend to pay attention to perfect octaves in scientific experiments? The speaker here hasn’t proven this theory impossible, therefore it’s a hole in the argument.

We’re asked to strengthen the argument, so my first guess is that the correct answer will plug the hole we have identified. Something like, “It’s impossible to learn to pay attention to perfect octaves,” would plug the gap nicely. Let’s see.

A) This is irrelevant, since the issue is whether humans have a “biological disposition” to perfect octaves. In other words, older kids and adults are irrelevant. The point is: do newborns do it? How about babies in the womb? That’s what we’re really interested in.

B) Okay, this is good. If this is true, then the babies in the study couldn’t have been indoctrinated. Instead, they’re naturally paying attention to perfect octaves. I like this answer.

C) Nah, who cares. It’s just not relevant if they heard music from one culture, or all cultures. What’s relevant is if they’d heard any music at all. B gets to that point.

D) Colors? **** off with that. Irrelevant.

E) I don’t see how this would possibly strengthen the argument. In fact, it’s probably a weakener, because if this is true then maybe the babies got indoctrinated during the study itself.

Our answer is B.

well, i guess babies are infact representing human beings here rather than generalizing.. Other cultures people who are adult also showed the same tendencies its already said..

I will go for "B" which proves that the judgement of the babies are not biased and anything that strengthens the source of a research statistics also strengthens the argument..

yet, would love to know more from other guyz out there

has to be "B"

only B nullifies any effect culture could have had on relating musical patterns.
additionally, it also states that the babies had no previous exposure to music.
so, it must certainly be hard-wired into one's biological setup.

A tempting. but what if cultural effects could have played a role?
C does not strengthen. not enough evidence.
D irrelevant
E does not strengthen. only brings in more doubt!

i hope my reasoning is right here.

as an aside, discerning odd patterns in music is super fun...

GMATPill, great explanation,
but I would just want nightblade354 GMATNinja and gmat1393 to validate the explanation.
Is filling a gap in an argument a better strengthener according to GMAT standards?

sharathnair14, it depends. Strengthen/weaken questions can attack anywhere in the passage. Sometimes it will be the actual premise, other times it will be the space between the premise(s) and conclusion.

Ans is easy if we pay attention to the word "biological predisposition"(possesses some internal quality that gives them an increased likelihood)
B defends the argument from attack that the sample was biased and hence the conclusion is not true.

EXPLANATION FROM POWER SCORE

Strengthen—CE. The correct answer choice is (B)

This stimulus presents yet another experiment from which the author draws a causal conclusion. A diverse group of six-month-olds listened to various musical intervals, and showed more interest in the intervals which are prevalent in the musical systems of most world cultures. The author concludes that this is based on a biological disposition:
Cause ..... ..... ..... ..... Effect

Biology ----> Interest is more prevalent musical intervals

Answer choice (B): This is the correct answer choice. The question asks us to strengthen this causal argument, so we should probably look for the answer choice which rules out other possible explanations for the experiment’s results. Answer choice (B) does exactly that. If none of the babies in the experiment had any prior exposure to any music, then this rules out the possibility that the preferences reflected in the experiment were based on familiarity rather than genetic predisposition.

Answer choice (A) does not strengthen the causal claim. The fact that the apparent preference for such intervals continues beyond childhood provides no insight into the initial cause for that preference. Answer choice (C) seems to weaken the author’s claim; if the babies were exposed to a lot of music, most of which reflected the most prevent musical intervals, then this provides an alternative cause (that is, familiarity) for the babies’ preference. Answer choice (D) is perhaps the most clearly irrelevant, since the whole discussion here centers around musical preferences, not color. Answer choice (E), like answer choice (C) above, provides an alternative cause for the babies’ general preferences—repetition/familiarity.

 

IanStewart
Thanks for the detailed explanation. I had the ACs narrowed down to A & B and spent almost 15mins debating why A can't be a strengthener.
Below are my thoughts to eliminate (A). I would appreciate your views here.
I think (A) is a premise booster. 
It has been mentioned in the stimulus that ''These intervals are prevalent in the musical systems of most cultures around the world.''
I think (A) adds nothing new to the argument. Rather, CAN BE inferred from the above premise.

This is a very good advice. There is no point learning rules in CR when one can use simple logic. ­­­­