“Fast cycle time” is a strategy of designing a manufacturing organizat

A presupposition is something that you are assuming to be true and then concluding your argument.
A questionable statement is something which may or may not be valid.

"A questionable presupposition" just means an assumption, the validity of which is questionable, but an assumption made by the author nevertheless. In essence, it is just an assumption question.
An assumption is something that must be necessary for the argument. The author assumes it to be true. Whether it actually is true or not, we don't have to worry about it. This question stem is telling us that the assumption he has made may not be valid.

Don't confuse this with given premises. Since the author gives them as data to back his conclusion, we assume the premises to be true while evaluating the validity of his argument.


Argument:

“Fast cycle time” is a strategy of designing a manufacturing organization to eliminate bottlenecks and delays in production.
bottlenecks and delays cannot be eliminated unless all work is done right the first time.

Conclusion: Not only does it speed up production, but it also assures quality.


(A) any flaw in work on a product would cause a bottleneck or delay and so would be prevented from occurring on a “fast cycle” production line

This is the missing link. It links quality (not mentioned in premises but concluded) to fast cycle.
The author is assuming that since the "fast cycle" eliminates bottle necks, it eliminates flaws too. The assumption is that flaws will cause a bottleneck. So removing bottlenecks means all flaws are taken care of.

(B) the strategy of “fast cycle time” would require fundamental rethinking of product design
Irrelevant. How we achieve fast cycle doesn't matter.

(C) the primary goal of the organization is to produce a product of unexcelled quality, rather than to generate profits for stockholders
Irrelevant. The argument discusses "fast cycle time" strategy. Whether organisations will use it or not, we don't have to worry.

(D) “fast cycle time” could be achieved by shaving time off each of the component processes in production cycle
How it is achieved - whether time is shaved off from each process or from some specific processes - doesn't matter.

(E) “fast cycle time” is a concept in business strategy that has not yet been put into practice in a factory
We don't know whether it has been put in practice. Our argument doesn't depend on it.

Answer (A)