Answer:
Among the options given on the question the best three reasons are given below.
1.Terrorists operate from various nations around the world= Terrorists do not only work or plan in USA. They operate the insurgency from various nations around the world. So if other nation also cooperate, it is for USA to fight the terrorists.
2.Other nations are also threatened by terrorists= USA is not only attacked or threatened by terrorists . There are many other countries that are attacked by them. Like as Britain, France, Spain and many other Western countries.
3.It is more effective to gather the resources and expertise of many nations= When a threat is working world wide it is more effective to fight against this threat by co operating each other with the resources and expertise. That's USA seeks foreign co operation for battle against terrorism.
Step-by-step explanation: