【单项选择题】
Refer to exhibits 1 and 2. A company uses a Metro Ethernet （Gigabit Ethernet） dedicated circuit to communicate between users （subnet B） and servers （subnet A） as shown in Exhibit 1. Both routers use OSPF to advertise the subnets. During a weekly management meeting， they realize that the WAN link is oversize. They have been using only 2 Mb/s in the worst-case scenario. So they propose a new， cheaper WAN connection using a 2-Mb/s Frame-Relay point-to-point link to interconnect both sites （Exhibit 2）. The Frame Relay service provider informs them 
A、A.Use OSPF network broadcast，because it uses unicast to establish a neighbor relationship.
B、B.Use OSPF network point-to-multipoint，because it uses unicast to establish a neighbor relationship.
C、C.Use OSPF network point-to-point，because it uses unicast to establish a neighbor relationship.
D、D.Use OSPF network point-to-multipoint nonbroadcast，because it establishes a neighbor relationship using unicast packets.
E、E.Use OSPF network nonbroadcast，because it establishes a neighbor relationship using multicast.
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