Router R1 exists in an Enterprise that uses EIGRP as its routing protocol. The show ip route command output on router R1 lists the following phrase: "Gateway of last resort is 1.1.1.1 to network 2.0.0.0". Whic h of the following is most likely to have caused this output to occur on R1?（）

A. R1 has been configured with an ip default- network 2.0.0.0 command.
B. R1 has been configured with an ip route 0.0.0.0 0.0.0.0 1.1.1.1 command.
C. R1 has been configured with an ip route 2.0.0.0 255.0.0.0 1.1.1.1 command.
D. Another router has been configured with an ip default - network 2.0.0.0 command.
E. Another router has been configured with an ip route 2.0.0.0 255.0.0.0 1.1.1.1 command.