正解:D
In a network, when a device can ping another device but extended pings fail, it often indicates a routing issue.
In this case, R1 can ping R3's fa0/1 interface, which means there is connectivity between the two routers.
However, the extended pings fail because R3 does not have a return route to the network 10.99.69.0/30.
Without this return route, R3 cannot send the echo replies back to R1, resulting in the failure of the extended pings.