providing performance feedback to pilots providing flight information to passengers increasing the number of aircraft at the airport increasing the number of runways at the airport
I gave my students this multiple choice question: Which of the following would be most effective in reducing air traffic congestion at a busy airport?

Only one answer is correct among these 4 choices:
- providing performance feedback to pilots
- providing flight information to passengers
- increasing the number of aircraft at the airport
- increasing the number of runways at the airport

Could you tell me which one is correct?

increasing the number of runways at the airport