Refer to the exhibit. EIGRP has been configured on routers R1 and R2. However， R1 does notshow R2 as a neighbor and does not accept routing updates from R2. What could be the cause ofthe problem？（）

• A、The no auto-summary command has not been issued under the EIGRP process on bothrouters
• B、Interface E0 on router R1 has not been configured with a secondary IP address of 10.1.2.1/24
• C、EIGRP cannot exchange routing updates with a neighbor’s router interface that is configuredwith two IP addresses
• D、EIGRP cannot form neighbor relationship and exchange routing updates with a secondaryaddress