In the 14th century, a landmass separated from the Californian coast,

Question

In the 14th century, a landmass separated from the Californian coast, isolating a species called the Boojum tree on the newly formed island, which is known today as Baja Island. The island trees that descended from this group produce creamy yellow flowers, whereas Boojum trees on the mainland produce pale pink flowers. Baja Island has year-round temperatures higher than that of the mainland. Therefore, the color of the Boojum flowers of Baja Island is influenced, at least to some extent, by the temperature changes that the island underwent. Which of the following is an assumption on which the argument depends?

A The number of Boojum trees on Baja Island has not significantly increased since the 14th century
B Since the 14th century, the mainland’s temperature has not changed in ways that have influenced the color of the Boojum flowers that bloom on the mainland
C None of the Boojum trees on Baja Island are known to be adversely affected by higher temperatures
D The soil on Baja island contains the same minerals, which influence the color of the Boojum flowers, as that on the mainland does
E The Boojum trees on Baja Island and those on the mainland are identical in all respects except for the color of their flowers

Source:Crackverbal

push12345 · Accepted Answer

D is trap here

Negating D gives us soil does not have same minerals which influence color on island

But here we don't know how much soil actually influence color
Suppose if it influence only 10percent then no major difference
But if it influence more than 80 percent then it is considerable

B on other side
Says make sure temperature on mainland does not result in change of color from yellow to pink

So B is better choice here

Give kudos if it helps

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hellosanthosh2k2 · Answer

Nice Question,

objection to argument? what if, yellow is normal color, and rather than temperature changes in Baja Island, temperature changes in mainland changed the normal color from yellow to pale pink.

Choice B eliminates this possibility

Valhalla · Answer

I think the answer is D.
The soil on Baja island contains the same minerals, which influence the color of the Boojum flowers, as that on the mainland does.
Negate:
The soil on Baja island DOES NOT contain the same minerals, which influence the color of Boojum flowers as that on the mainland does 
Weaken the conclusion by introducing an alternate explanation for the color of flowers

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SonalSinha803 · Answer

A The number of Boojum trees on Baja Island has not significantly increased since the 14th century
- irrelevant

B Since the 14th century, the mainland’s temperature has not changed in ways that have influenced the color of the Boojum flowers that bloom on the mainland
- it says why colour of the boojum flowers are pink. Hold

C None of the Boojum trees on Baja Island are known to be adversely affected by higher temperatures
- does not talk about colour. Irrelevant

D The soil on Baja island contains the same minerals, which influence the color of the Boojum flowers, as that on the mainland does
- very indirect. Cannot be an assumption.

E The Boojum trees on Baja Island and those on the mainland are identical in all respects except for the color of their flowers
- irrelevant

IMO B.

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SajjitaKundu · Answer

Can we get a proper explanation to why D is incorrect?

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pn091 · Answer

@SajittaKundu  D is incorrect  because the conclusion states that "the color of the Boojum flowers of Baja Island is influenced,  at least to some extent , by the temperature changes that the island underwent", thereby already acknowledging that other factors bringing the change in colour might be present. The argument therefore only hinges on the temperature aspect which is well accounted for in B.

AG95 · Answer

GMATNinja   GMATNinjaTwo   Bunuel  @veritasprep 
Can someone please explain why option D is incorrect ?

D says soil might have some minerals which are responsible for the color difference in the mainland and island. 
If this is true that conclusion is wrong that it is because of temperature difference.

arushi118 · Answer

The passage does not say that the colour change is entirely due to the temperature difference. So it can be that part of the difference is due to different minerals in soil and part due to temperature difference.

B on the other hand gives us an option that what if the temperature of main land changed and caused the flowers to change their colour instead of the other way round (flowers on island changing colour). - This is because we don't know what their colour was initially. so could have changed from pink to yellow or yellow to pink.

SafSin28 · Answer

Argument skeleton:
P1: There are two types of trees differed in flower colors in separated island and a mainland.
P2: The temperature in island is different from that of mainland. 
C: Therefore, the temperature is somewhat responsible for difference in flower color of the Boojum in the island.
Assumption: 1) It is really the case that only the flower color of the tree in island is somewhat influenced by temperature AND The conditions in the mainland has stayed the same since the separation .
A The number of Boojum trees on Baja Island has not significantly increased since the 14th century-----> Irrelevant as "number of trees" is not discussed in P or C. OUT
B Since the 14th century, the mainland’s temperature has not changed in ways that have influenced the color of the Boojum flowers that bloom on the mainland. ----> This is about the conditions for the mainland stays the same. So keep it.
C None of the Boojum trees on Baja Island are known to be adversely affected by higher temperatures. -----> But we are not looking for the effect of temperature on trees. OUT
D The soil on Baja island contains the same minerals, which influence the color of the Boojum flowers, as that on the mainland does. ----> Ok, this does target the conclusion, although conclusion avoids such concerns by saying "at least to some extent". But it does not cover the premises, so OUT.
E The Boojum trees on Baja Island and those on the mainland are identical in all respects except for the color of their flowers. ---> This is a premise booster/ just descriptive of the background, so OUT.
It is B.

In the 14th century, a landmass separated from the Californian coast,

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In the 14th century, a landmass separated from the Californian coast,

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