Young whales, not yet ready to mate, tend to stay out in the

Question

Young whales, not yet ready to mate, tend to stay out in the open ocean and move continually. Barnacle larvae, looking to find a whale to attach themselves to, are unable to latch onto these young whales. Adult whales, however, move into warm, shallow water to mate, and stay more or less in one place while mating, giving the barnacles an opportunity to attach to them. Surprisingly, young sperm whales, even though they tend to stay in the shallower water where they are born for the first year of their life, are found not to have many barnacles growing on them

Which of the following, if true, best helps to explain this surprising finding?

a)The chemical cue released by whales into the water, which lets barnacle larvae know there is a whale nearby, is lacking in sperm whales.
b)A whale carrying a very large barnacle population on its skin has greater difficulty attracting a mate.
c)The population of barnacle larvae can vary greatly from one shallow area of the ocean to another.
d)Barnacle larvae are most prevalent and can survive for the longest periods of time in warm, shallow water.
e)The stronger currents out in the open ocean do not themselves knock barnacles loose

Please explain option b ?

raiprem123 · Answer

PREMISE1: Young whales tend to stay out in the open ocean and move continually. Barnacle larvae, looking to find a whale to attach themselves to, are unable to latch onto these young whales.
PREMISE2 : Adult whales move into warm, shallow water to mate, and stay more or less in one place while mating, giving the barnacles an opportunity to attach to them. 
CONCLUSION : young sperm whales, even though they tend to stay in the shallower water where they are born for the first year of their life, are found not to have many barnacles growing on them

Which of the following, if true, best helps to explain this surprising finding?

a)The chemical cue released by whales into the water, which lets barnacle larvae know there is a whale nearby, is lacking in sperm whales.
 CORRECT :   This is a sufficient reason to explain the conclusion of the paragraph. If the larvae are unable to sense presence of sperm whales due to lack of chemical cue released, they will not attach to these whales. 
b)A whale carrying a very large barnacle population on its skin has greater difficulty attracting a mate.
 WRONG : NOT MENTIONED. In no way it supports or explains the conclusion. 
c)The population of barnacle larvae can vary greatly from one shallow area of the ocean to another.
 WRONG: Nothing can be inferred from this as the variation from one to another area can be either positive or negative. 
d)Barnacle larvae are most prevalent and can survive for the longest periods of time in warm, shallow water.
 WRONG: Both young and Adult whales come to the shallow, warm water area but larvae are attached to Adults only. So there must be some other reason for this surprising phenomenon. 
e)The stronger currents out in the open ocean do not themselves knock barnacles loose
 WRONG: Neither supports not opposes

Please explain option b ?

pqhai · Answer

Hi 2013gmat. I'm glad to help.

ANALYZE THE QUESTION:

In "resolve the paradox question",   understand the paradox is KEY  . Even though the wording in this question is quite convoluted, the main idea is:
 Fact:   Adult whales move into warm, shallow water to mate, and stay more or less in one place while mating ==> giving the barnacles an opportunity to attach to them.
 Fact:  Young sperm whales also tend to stay in the shallower water where they are born for the first year of their life, are found not to have many barnacles growing on them

Generalize the stimulus:  why young sperm whales live in the “ same condition ” as the adult whales do, but the young sperm whales  do not have many barnacles growing  on them. ==> There must be  a factor  (other than the strong level of currents in shallow water) that affects the attachment of the barnacles on whales

ANALYZE THE ANSWERS:

a)The chemical cue released by whales into the water, which lets barnacle larvae know there is a whale nearby, is lacking in sperm whales.
  Correct.   Option A explains why barnacle can't grow on young sperm whales because young sperm whales do not release “signal” for barnacles. Thus, these barnacles cannot find their “targets”.
 
b)A whale carrying a very large barnacle population on its skin has greater difficulty attracting a mate.
 Wrong.  B just help to explain why whales having fewer barnacles can attract mates more effectively. Thus, B does not help to explain  the paradox  why young sperm whales live in the same condition as the adult whales do not have barnacles growing on them. (if you understand the paradox, you can eliminate B quickly because B provides nothing to resolve the paradox).

c)The population of barnacle larvae can vary greatly from one shallow area of the ocean to another.
 Wrong.  The density of barnacle does not explain why those barnacles do not grow on young sperm whales, but adult whales.

d)Barnacle larvae are most prevalent and can survive for the longest periods of time in warm, shallow water.
 Wrong.  Same as C. D does not help to resolve the paradox.

e)The stronger currents out in the open ocean do not themselves knock barnacles loose
 Wrong.  Shift the object. We’re talking about the barnacles in the shallow water, not about open ocean.

Hope it helps.

nitin6305 · Answer

How did you assume this? It is nowhere mentioned in the stimulus that shallow water has stronger currents.

pqhai · Answer

Hi nitin My wording may make you get confused. However, I do not mean shallow water has stronger currents. I mean "the strong level of currents" which differs from "the strong currents". In fact, shallow water cannot bear strong currents.

I want to convey the idea that there is another factor contributing to the growing of barnacle on Whales. The stimulus, however, only focuses on "the strong level of currents". The stimulus says that barnacles can grow on whales because the currents in shallow water is weak, making the barnacles easy to grow. The case is not correct for young sperm whales <== this is the paradox we need to explain. Hope it's clear now.

blueseas · Answer

argument says : barnacles grow on whales ,which are stationary for long time and donot move continually(see highlited part)

now it says adult whales =>stay in shallow water for long and remain almost stationary.
more sperm whales(just born whales)==>they also stay in shallow water and they are also stationary.
  difference between these two whales =>adult whales: they have barnacles while SPERM WHALES donot.
 ]so this is the paradox.

clearly A resolves out the paradox keeping both condition under consideration: 
it says:
a)The chemical cue released by whales into the water, which lets barnacle larvae know there is a whale nearby, is lacking in sperm whales.
  it says that barnacles are not aware of presence of SPERM WHALES thats why they dont target SPERM whales ,thus resulting to no barnacles on SPERM WHALES.

HOPE IT HELPS

2013gmat · Answer

Thank you everyone for great explanations.
You guys ROCK!!

VectorSS · Answer

Unless I completely missed it, no where does it say that young sperm whales remain in shallow AND  warm  water. It only states they stay in shallow water; what if the water was cold?

Because of this, I chose D. Am I over analyzing?

animanga008 · Answer

(D) wouldn't work because there is no mention of water temp and barnacle/whale relationship.

mvictor · Answer

I like solve the paradox type of questions :D

because - correct answer choice, young sperm whale have fewer barnacles in warm, cold waters where they live for the first time of the year, while the adult whales in the similar condition waters have problems with barnacles.

only answer A perfectly fits in this magic formula.

the other answers are out of scope, and do not provide any information that would actually solve the discrepancy.

VerbalBot · Answer

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Young whales, not yet ready to mate, tend to stay out in the

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