Which of these can you use to effectively and dynamically reduce IP address spoofing?

A network design shows two routers directly connected to an Ethernet switch using optical connections.
There is an OSPF adjacency between the routers. In this design, which solution will ensure that interface down detection is reported as quickly as possible to the IGP?

As part of the security protocol for your network design, you have designated that option 82 is enabled for DHCP snooping. When option 82 is enabled, which information will be added to the DHCP request?

A network administrator is having problems with redistribution routing loops between two
EIGRP processes.
You've looked at the configurations and determined there is no filtering configured on the routes being redistributed. To avoid having a single point of failure, there are three routers configured to redistribute between the two routing protocols. Which solution would you recommend to minimize management complexity?

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 routes on the network -

From a design perspective, what was not taken into account prior to implementing the solution?