"This company will not be training any more pilots in the foreseeable future, since we have 400 trained pilots on our waiting list who are seeking employment. The other five major companies each have roughly the same number of trained pilots on their waiting lists, and since the projected requirement of each company is for not many more than 100 additional pilots, there will be no shortage of personnel despite the current upswing in the aviation industry. " Which one of the following, if true, casts the most doubt on the accuracy of the above conclusion? ['Most of the trained pilots who are on a waiting list for a job are on the waiting lists of all the major companies.', 'Some of the other major companies are still training pilots but with no presumption of subsequent employment.', 'The quoted personnel projections take account of the current upswing in the aviation industry.', 'In the long run, pilot training will become necessary to compensate for ordinary attention.']