Northern Air has dozens of flights daily into and out of Belleville Airport, which is highly congested. NorthernAir depends for its success on economy and quick turnaround and consequently is planning to replace its large planes with Skybuses, whose novel aerodynamic design is extremely fuel efficient. The Skybus' fuel efficiency results in both lower fuel costs and reduced time spent refueling. Which of the following, if true, could present the most serious disadvantage for Northern Air in replacing their large planes with Skybuses? ['Aviation fuel is projected to decline in price over the next several years.', 'The Skybus would enable Northern Air to schedule direct flights to destinations that currently require stops for refueling.', 'The aerodynamic design of the Skybus causes turbulence behind it when taking off that forces other planes on the runway to delay their takeoffs.', "None of Northern Air's competitors that use Belleville Airport are considering buying Skybuses."]