After the Recent Implementation of a New Design That Incorporated

Multiple Choice

After the recent implementation of a new design that incorporated GRE tunnels into the network, the network operations staff is seeing the following syslog message in multiple routers on the network - %TUN-5-RECURDOWN: Tunnel0 temporarily disabled due to recursive routing. From a design perspective, what was not taken into account prior to implementing the solution?

A) The neighboring routers cannot respond within the specified hold time.
B) The interface on the router that is the source of the tunnel is down.
C) The interface on the neighboring router that is the source of the tunnel is down.
D) The router is learning the route to the tunnel destination address using the tunnel interface.
E) The tunnel interface on the router is not receiving any keepalives within the specified hold time.