【单选题】

For each blank, choose the best answer from the four choices and write down on the answer sheet.(66) is a protocol that a host uses to inform a router when it joins or leaves an Internet multicast group.(67) is an error detection code that most data communication networks use.(68) is an interior gateway protocol that uses a distance vector algorithm to propagate routing information.(69) is a transfer mode in which all types of information are organized into fixed form cells on an asynchronous or non-periodic basis over a range of medi

A、(70) is an identifier of a web page.
A、ICMP
B．SMTP
C．IGMP
D．ARP