Why is the Branch2 network 10.1 0.20.0/24 unable to communicate with the Server farm1 network 10.1 0.10.0/24 over the GRE tunnel?

On R2:

We see interfaces Tunnel0 at two ends are “up/up” which are good so we should check for the routing part on two routers with the “show running-config” command and pay attention to the static routing of each router. On Branch2 we see:

The destination IP address for this static route is not correct. It should be 192.168.24.1 (Tunnel0’s
IP address of R2), not 192.168.24.10 -> Answer C is correct.
Note: You can use the “show ip route” command to check the routing configuration on each router but if the destination is not reachable (for example: we configure “ip route 10.10.10.0
255.255.255.0 192.168.24.10” on Branch2, but if 192.168.24.10 is unknown then Branch2 router will not display this routing entry in its routing table.
Note: The IP address or configuration may be different in the exam.