Refer to the exhibit. EIGRP had converged in AS 1 when the link between router R1 and R2 went down. The console on router R2 generated the following messages: *Mar 20 12:12:06: %DUAL - 5NBRCHANG E: IP - EIGRP 1: Neighbor 10.1.4.3 (Serial0) is down: stuck in active *Mar 20 12:15:23: %DUAL -3- SIA: Route 10.1.1.0/24 stuck - in - active state in IP - EIGRP 1. Cleaning up The network administrator issued the show ip eigrp topology active command on R2 to check the status of the EIGRP network. Which statement best describes the reason for the error messages?（）