Refer to the network shown below： R1 and R2 belong to the RIP routing domain that includes the networks 10.20.0.0/16 and 10.21.0.0/16. R3 and R4 are performing two-way route redistribution between OSPF and RIP. Anetwork administrator has discovered that R2 is receiving OSPF routes for the networks 10.20.0.0/16 and 10.21.0.0/16 and a routing loop has occurred. Which action will correct thisproblem？（）

• A、Set the OSPF default metric to 20
• B、Apply an inbound ACL to the R2 serial interface
• C、Configure distribute-lists on R3 and R4
• D、Change the RIP administrative distance on R3 to 110
• E、Change the OSPF administrative distance on R3 to 110
• F、None of the other alternatives apply