Major airlines will purchase many of the new aircrafts

Major airlines will purchase many of the new aircrafts capable of carrying more than 500 passengers on transcontinental and transoceanic flights. These airlines currently rely on "hub and spoke" systems of routing, in which large planes, which can seat 400 people and are capable of transoceanic flight, fly into hubs that have runways sufficiently long to handle them. From there, passengers are dispatched to local airports on connecting flights on small planes. With takeoff and landing time slots almost completely booked at most hubs, and little new runway construction expected, airlines will want to expand the volume of passengers they can fly in a given time slot.

The argument above would be most weakened if which of the following were true?

A. The new 500 seat aircraft cost more per seat than existing aircraft
B. Air traffic control systems at most hub airports cannot handle any more flights per hour than they currently do
C. The new 500 seat aircraft require boarding times substantially longer than those of existing aircraft
D. Small passenger aircraft, capable of efficient transcontinental and transoceanic flight and able to land on short runways, have come into service
E. Transoceanic air flights are currently running at near maximum capacity

The OA is D.

Please, explain to me what is your reasoning in each option. How can I select the right option?