Two small-business owners, Jensen and Ling, could not be more different. Jensen is easy going, easy to talk to, good at delegating responsibility, and quick to acknowledge the contributions of others. Ling, however, is often high strung, generally unfriendly, and unable to give up any authority; she is determined to be involved in every decision. This explains why Jensens business is successful while Lings business has failed.

The conclusion of this argument is based upon all of the following assumptions EXCEPT

Let's jot down the points:
Premise: j≠l
Premise: j personality +ve and l personality -ve
Premise: ?
Conclusion: Therefore, business success j>l

We need to find this 4 such unstated premise (assumption) and mark the 5th option as the answer.

A. the personality of a business owner is the main factor in the success of the business.
INCORRECT. This could be an assumption. The argument is comparing personalities and because of which success in business mattered at the end.

B. a business leader with Jensen’s type of personality is more effective than one with Ling’s personality.
INCORRECT. This could be an assumption. This strongly supports the conclusion.

C. Jensen and Ling were in direct competition with each other.
CORRECT. The entire argument is talking about personalty differences of two individuals that could have lead to their individual business to success/failure. Nowhere in the passage there is even a small sign to show us that they were in competition with each other. How does this even matter?

D. Jensen and Ling had similar educational backgrounds and a comparable level of business experience.
INCORRECT. This sentence would be a sound assumption. If j=l and yet because of their personality differences, business succeeded/failed...yes that makes sense.

E. Jensen and Ling had comparable businesses operating under comparable circumstances.
INCORRECT. This sentence would be a sound assumption like option E. If j=l, comparing both businesses is accurate measure. Otherwise it would have been like j has big business and l has small business that is why l failed? This doesn't sound right for this argument. This assumption removes this confusion.

The conclusion of this argument is based upon all of the following assumptions EXCEPT

A. the personality of a business owner is the main factor in the success of the BUSINESS.
This assumption connects all premises to the conclusion of the argument. Negating this assumption would weaken the conclusion.

B. a business leader with Jensen’s type of personality is more effective than one with Ling’s personality.
This assumption connects well all premises to the conclusion of the argument. Negating this assumption would weaken the conclusion.

C. Jensen and Ling were in direct competition with each other.
CORRECT ANSWER. Negating this assumption will neither weaken or strengthen the conclusion.

D. Jensen and Ling had similar educational backgrounds and a comparable level of business experience.
This assumption links well all premises to the conclusion of the argument. Negating this assumption would weaken the conclusion.

E. Jensen and Ling had comparable businesses operating under comparable circumstances.
This assumption links well all premises to the conclusion of the argument. Negating this assumption would weaken the conclusion.

CORRECT ANSWER is (C)

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IMO C, because it's out of scope.

The conclusion of this argument is based upon all of the following assumptions EXCEPT

A. the personality of a business owner is the main factor in the success of the business.
B. a business leader with Jensen’s type of personality is more effective than one with Ling’s personality.
C. Jensen and Ling were in direct competition with each other.
D. Jensen and Ling had similar educational backgrounds and a comparable level of business experience.
E. Jensen and Ling had comparable businesses operating under comparable circumstances.

Answer C.
The argument is comparing two different cases on the basis of one factor only (personality), and explaining a different result through this factor. This requires assuming this factor is the relevant one, and all other factors are equal - which is what A,B,D and E do.
Assuming the two are in competition, on the other hand, is unnecessary. They could be in entirely different fields and the logic would still hold.
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The answer is A in my opinion. All the other options in line with the evidences in stimulus presented a form of comparison between Ling and Jensen which is very key to the structure of the argument, which is basically comparing Jensen and Ling. Yes it is true that the personality of a business owner is a main factor in the success of a business. But what kind of personality is good and which kind is bad? An assumption is an unstated evidence in an argument based on which a conclusion is drawn. It should bridge the gap between the evidences provided and the conclusion. A is not bridging any gap since it is just a mere restatement of potions of the argument.

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Two small-business owners, Jensen and Ling, could not be more different. Jensen is easy going, easy to talk to, good at delegating responsibility, and quick to acknowledge the contributions of others. Ling, however, is often high strung, generally unfriendly, and unable to give up any authority; she is determined to be involved in every decision. This explains why Jensens business is successful while Lings business has failed.
The conclusion of this argument is based upon all of the following assumptions EXCEPT.

The argument is based upon that the businesses are small run by two different owners having different personality. Jensen is easy going and has other leadership skills is successful as compared to Ling whose business has failed. Since it’s an EXCEPT question answer would be an assumption that does n't make any difference to the argument.

A. the personality of a business owner is the main factor in the success of the business. – WRONG. That’s what argument says in its conclusion if not exactly.
B. a business leader with Jensen’s type of personality is more effective than one with Ling’s personality. – WRONG. Argument falls apart if this is not the assumption considered.
C. Jensen and Ling were in direct competition with each other. – WRONG. ‘Two small – business owners’ suggests that they both were in competition.
D. Jensen and Ling had similar educational backgrounds and a comparable level of business experience. – CORRECT. Had that Jensen was an experienced businessman and Ling a newbie with both having different set of qualification the argument’s conclusion would hold strong.
E. Jensen and Ling had comparable businesses operating under comparable circumstances – WRONG. The comparison drawn by the argument shows that both operated in similar situations – small business.

Answer (D).
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Hard to choot between A & b,

While effectiveness can be irrelevant, passage doesn't talk about main factor.

Hence A

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IMO it's C because the direct or indirect competition is not something talked about in this argument hence it would not matter.

Two small-business owners, Jensen and Ling, could not be more different. Jensen is easy going, easy to talk to, good at delegating responsibility, and quick to acknowledge the contributions of others. Ling, however, is often high strung, generally unfriendly, and unable to give up any authority; she is determined to be involved in every decision. This explains why Jensens business is successful while Lings business has failed.

The conclusion of this argument is based upon all of the following assumptions EXCEPT

C. Jensen and Ling were in direct competition with each other.
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Official Explanation

Correct Answer: C

Jensen and Ling did not have to be in direct competition with each other; indeed, they did not even have to know the other business existed. Rather, this argument hinges on other important assumptions. Clearly, the most important assumption is a, that the business leaders personality is the main factor in the businesss success or failure. The premises focus on the personality traits of Jensen and Ling and jump to the conclusion that their personalities made the difference in their business success. Choice b is incorrect for the same reason; it also forms a logical link between the premises and the conclusion. Choices d and e are incorrect because they state assumptions that are essential in making this an apples-to-oranges comparison. Whatever their personality differences, this comparison does not work if Jensen and Ling were not similarly equipped (with education and experience) and in comparable businesses operating under comparable circumstances
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