A “device unreachable” event has been detected by the NMS. The NMS has also performed automated routines and determined that no interfaces are reachable (routed or directly connected). The last few log entries stored on the logging server for this device are as follows:
What is the most probable cause of the outage?

A.
The device overheated, causing a system shutdown.

B.
An unauthorized change was made, which caused the outage.

C.
Routing flaps are causing the device to become unreachable.

D.
An OSPF dead timer has caused the device to lose its adjacency.