Which of these statements accurately identifies how Unicast Reverse Path Forwarding can be employed to prevent the use of malformed or forged IP sources addresses？（）

• A、It is applied only on the input interface of a router.
• B、It is applied only on the output interface of a router.
• C、It can be configured either on the input or output interface of a router.
• D、It cannot be configured on a router interface.
• E、It is configured under any routing protocol process.