Self-study
Manufacturer: Support If our biggest competitor were to go out of business, some of the specialized suppliers that we both use would be bankrupted. ███ ██ █████ ███ ██ ██ ████ ██ █████████ ███ ███████ ██████████ ████ ████ ██ █████████
Argument Summary
We start with a premise establishing that if the author's biggest competitor goes out of business, some specialized suppliers used by both the author and the competitor would go bankrupt. Thus, the author concludes, the biggest competitor's avoidance of bankruptcy is necessary for the author to stay in business. Another way to express the conclusion is that if the biggest competitor goes out of business, then the author would also go out of business.
Objective: Bridge the Gap
As with many Sufficient Assumption questions, there's a gap between the premises and a new concept in the conclusion. It's easier to see this gap and the bridge we need to build to bridge this gap through a diagram:
Premise: biggest competitor out of business → some suppliers bankrupt
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Conclusion: biggest competitor out of business → manufacturer (the author) out of business
Notice how the conclusion asserts that something will lead to the author going out of business? But the premise doesn't say anything about what will lead to the author going out of business. That tells us, at a minimum, that the correct answer should tell us what is sufficient for the author to go out of business. Since we already know from the premise that the biggest competitor's bankruptcy is sufficient for some specialized suppliers to go out of business, we can prove the conclusion by adding the claim that some specialized suppliers going out of business is sufficient for the author to go out of business. Or, in other words, in order for the author to stay in business, none of the specialized suppliers that it has in common with its biggest competitor can go out of business. Here's what that looks like in diagram form:
Premise: biggest competitor out of business → some suppliers bankrupt
Missing bridge: some suppliers bankrupt → manufacturer (the author) out of business
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Conclusion: biggest competitor out of business → manufacturer (the author) out of business
17.
The conclusion drawn above follows █████████ ██ █████ ███ ██ ███ █████████ ██ ████████
a
The manufacturer's specialized █████████ ████ ███ ██ ███████████
This doesn't say anything about what's required in order for the manufacturer to stay in business. Since the premise also doesn't say anything about this, (A) can't make the argument valid. Remember, for a Sufficient Assumption question, if there's a concept in the conclusion that isn't covered as part of the premises ("in order for us to stay in business" is a new concept in the conclusion), then the correct answer, at a minimum, must establish something about that concept. If we pick an answer that doesn't establish something about that new concept, then we have no way to guarantee the conclusion.
b
The manufacturer will ████ ██ ████████ ██ ███ ███████ ██████████ █████ ██ █████████
This is a sufficiency-necessity confused version of the conclusion. The conclusion asserts that the biggest competitor's staying in business is necessary in order for the author to stay in business ("...our biggest competitor must stay in business"). (B) states that the biggest competitor's staying in business is sufficient for the author to stay in business ("if its biggest competitor stays in business..."). But learning what's sufficient for the author to stay in business does not guarantee what's necessary for it to stay in business.
c
If the manufacturer ████ ███ ██ █████████ ███ ███████ ██████████ ████ ██ ███ ██ █████████
This is a sufficiency-necessity confused version of the conclusion. In fact, it's expressing the exact same relationship as (B) (just in the contrapositive form)! The conclusion asserts that the biggest competitor's staying in business is necessary in order for the author to stay in business ("...our biggest competitor must stay in business"). (C) states that the biggest competitor's staying in business is sufficient for the author to stay in business. To understand (C) in this way, it helps to recognize that "If author goes out of business, then competitor goes out of business" (what (C) says) means the same thing as "If competitor stays in business, then author stays in business." But, as with (B), learning what's sufficient for the author to stay in business does not guarantee what's necessary for it to stay in business.
d
The manufacturer will ████ ██ ████████ ██ ███ ███████████ █████████ ███ ███ ███████████
This is a sufficiency-necessity confused version of the bridge we want to build. We want to establish "if suppliers go out of business, then the author will out of business." But (D) states "if suppliers do not go out of business, then author will not go out of business." This establishes that the suppliers' staying in business is sufficient for the author's company to survive; but it doesn't establish that the suppliers' staying in business is necessary for the author's company to survive.
e
The manufacturer will ████ ██ ████████ ████ ██ ███ ███████████ █████████ ███ ███ ███████████
If we consider (E) and the premise together, the argument is valid. We know from the premise that if the biggest competitor goes out of business, the suppliers also go out of business. (E) tells us that if the suppliers go out of business, then the author will also go out of business. ("Only if" introduces a necessary condition. So (E) means "author stays in business → suppliers stay in business," which also means "supplies go out of business → author goes out of business.")