Following a Crash of an Amtrak Train Between Philadelphia and New

Multiple Choice

Following a crash of an Amtrak train between Philadelphia and New York,the eastern corridor north-south route was shut down.Commuters between Washington,D.C.,Philadelphia,and New York City were affected.Many had to resort to air travel.At the time of the shut-down,the airlines serving this corridor raised their airfares.Commuters complained that they were quoted prices of $2,000 for air fares in the route that normally ranged from $300-$500.What would constitute an antitrust violation?​

A) ​if the airlines raised their rates in response to the new demand
B) ​if the airlines communicated to each other about raising the fares
C) if there was conscious parallelism on raising the fares
D) if the rates were higher than Amtrak rates