The passage claims that the company will not be training any more pilots in the foreseeable future and that there will be no personnel shortage in the industry. This is because there are 400 trained pilots on the employee waiting list for the company, as is the case with the other five major companies as well. The projected requirement for each company is not more than 100 pilots, and since there are 400 pilots on each list, there should be no shortage.
(A) brings to light the possibility that most of the 400 trained pilots on the various companies' employment lists may be the same people, as opposed to 400 different people applying to each company with no overlap between company lists. If most of the listed pilots were overlaps, there would be a shortage because we would have slightly more than 400 pilots total despite each of the six companies needing around 100 pilots (for a total of 600 pilots needed). Since (A) casts doubt on the passage by pointing this possibility out, it is correct.
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