It was awful to think that there had been 4 planes hijacked that day , and how it could get much , much worse . Later that night when I got home , I was glued to the TV .... watching in horror as the Twin Towers came down and all the rescue workers and other people who were trapped in the buildings as they fell . It all seemed so surreal . So , so sad . At that time they thought there may have been 50,000 people in the building , and so many people were missing .
According to the above context, choose the best option to answer the following question.
Question: What happened after this event because of it ?
Options:
- The world was scared of a nuclear war between the US and Russia
 - People lost their jobs in the recession
 - Airport security increased
 - The stock market crashed and took years to recover


Airport security increased