Which default static route command would allow R1 to potentially reach all unknown networks on the Internet?

1) ip route 0.0.0.0 0.0.0.0 Serial0/0/0
2) ip route 0.0.0.0 0.0.0.0 Serial0/0/1
3) ip route 0.0.0.0 0.0.0.0 Serial0/1/0
4) ip route 0.0.0.0 0.0.0.0 Serial0/1/1

The correct answer would be option 1) ip route 0.0.0.0 0.0.0.0 Serial0/0/0. This command specifies that all unknown networks should be sent to the next-hop address specified by the Serial0/0/0 interface.