Your network contains two DHCP servers named Server1 and Server2. Server1 and Server2 are located in the same subnet.You configure a split scope named Scope1 on the DHCP servers.You need to ensure that Server2 only responds to DHCP client requests if Server1 is unavailable.What should you modify？（）

• A、the Scope1 properties for Server1
• B、the Scope1 properties for Server2
• C、the server options for Server1
• D、the server options for Server2