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## Assumption

tagged by: Roland2rule

### Top Member

Roland2rule Legendary Member
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#### Assumption

Sun Oct 29, 2017 11:46 am
Researchers studying the spread of the Black Plague in sixteenth-century England claim that certain people survived the epidemic because they carried a genetic mutation, known as Delta-32, that is known to prevent the bacteria that causes the Plague from overtaking the immune system. To support this hypothesis, the researchers tested the direct descendants of the residents of an English town where an unusually large proportion of people survived the Plague. More than half of these descendants tested positive for the mutation Delta-32, a figure nearly three times higher than that found in other locations.

The researchers' hypothesis is based on which of the following assumptions?
(A) Delta-32 does not prevent a carrier from contracting any disease other than the Plague.
(B) The Plague is not similar to other diseases caused by bacteria.
(C) Delta-32 did not exist in its current form until the sixteenth century.
(D) No one who tested positive for Delta-32 has ever contracted a disease caused by bacteria.
(E) The Plague does not cause genetic mutations such as Delta-32.
OA is e

why do you think option E is incorrect? Do you feel otherwise? please explain. Thanks

### GMAT/MBA Expert

ErikaPrepScholar Master | Next Rank: 500 Posts
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Thu Nov 16, 2017 10:07 am
The researchers' hypothesis is that "certain people survived the [Black Plague] epidemic because they carried a genetic mutation, known as Delta-32". They then supported this hypothesis by testing people who's ancestors survived the plague - they were found to have a high frequency of Delta-32. We need to find an assumption that this hypothesis or its evidence relies on. In other words, we need to find an answer choice where, if it were untrue, the researchers' hypothesis or its evidence would no longer be valid.

A. We don't care about any disease other than the plague. Whether or not they could get other diseases doesn't impact their ability to survive the plague. This answer is out of scope. Eliminate.
B. Like with A, we don't care about other bacteria. We know that Delta-32 impacts plague bacteria, which is all that matters to surviving the plague. Eliminate.
C. The plague occurred in the 16th century, so Delta-32 would have been around at the same time as the plague. If Delta-32 hadn't existed in its currently form until the 17th century, then this would matter, but it doesn't. Eliminate.
D. Again, we don't care about diseases caused by other bacteria. We just care about whether people with Delta-32 contracting the plague. Eliminate.
E. Let's consider what would happen if this were not true. What if the plague DID cause Delta-32? This would mean that its likely the reason that the descendants of plague survivors so frequently have Delta-32 is because their ancestors obtained Delta-32 due to the plague, survived due to chance/some other factor, and passed on the Delta-32 mutation to their descendants. This would indicate that the support for the researchers' hypothesis is invalid. So the researchers' hypothesis relies on this statement being true.

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### Top Member

VJesus12 Master | Next Rank: 500 Posts
Joined
14 Oct 2017
Posted:
211 messages
Thu Nov 16, 2017 7:50 am
I don't understand why the correct answer is E .

Can any expert help us here. I would like to know how to solve this CR question.

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