n your Cisco EIGRP network， you notice that the neighbor relationship between two of your routers was recently restarted. Which two of these choices could have made this occur？（）
- AAn update packet with init flag set from a known， already established neighbor relationship was received by one of the routers.
- BThe ARP cache was cleared.
- CThe counters were cleared.
- DThe IP EIGRP neighbor relationship was cleared manually.