This question is about the formation of OSPF adjacency. An OSPF adjacency will not form correctly across a point-to-point link in the same area. Which would most likely cause this problem？（）

A. Each interface has a different OSPF cost.
B. Each interface is configured with secondary addresses as well as primary addresses.
C. Each interface has a different MTU size.
D. Each interface is configured with theip unnumbered loopback 0 command.