The Internet Is a Hierarchical Structure Linking Different Levels of Service

The Internet is a hierarchical structure linking different levels of service providers whose millions of devices supply all the interconnections.The three levels outlined in the book from the top down include _____________________.

A) new system provider (NSP) ,current system provider (CSP) ,and order entry system provider (OSP)
B) national service provider (NSP) ,regional service provider (RSP) ,and Internet service provider (ISP)
C) net server point (NSP) ,radio server point (RSP) ,and Internet server point (ISP)
D) None of these choices