CIS .com recently acquired a smaller competitor. The acquired company is not currently using Cisco routers, so you have connected the two WANs via an authenticated PPP link. After configuration both routers, issuing the show interface s0/0 command on the Cisco Router shows the interface to be in the up/down state. Which two of these are possible causes? （）

• A、Bandwidth statements do not match
• B、MTUs do not match
• C、IP Addresses are not in the same subnet
• D、CHAP passwords do not match