hello!
I think that the answer is religion but I might be wrong
good luck!
Answer: Opportunity.
Explanation: Since the attack, <em>every year </em>Americans gather at the site of the ancient towers to honor the victims. In addition to the deaths, thousands of people developed cancer and lung disease, due to the toxic cloud that glided for weeks over the south of the city.
People become closer, and the American Greetings took the opportunity.
The answer to your question is proselytism. I hope that this helps you. :)