If an Airline Company Has Several Empty Seats on a Flight

Multiple Choice

If an airline company has several empty seats on a flight and the full price of an air ticket is $500 and the marginal cost per passenger is $100, then it will be profitable for the airline to

A) charge a stand-by passenger no less than the full fare of $500.
B) charge a stand-by passenger less than $100.
C) charge a stand-by passenger more than $500.
D) charge a stand-by passenger more than $100.
E) fill the seats at the last minute for any price.