Each circle is a router, each line is a connection, and the lines with arrows indicate connections to further routers on the Internet. How many single points of failure would the network administrator find

Two students are discussing electricity that has a frequency of 60 hz. student a says that this type of electricity is referred to as ac. student b says that in this type of electricity, the electrons flow in only one direction. which of the following statements is correct? a. only student a is correct b. only student b is correct c. both of the two students are correct d. neither of the two students is correct