You work as the enterprise exchange administrator at TestKing.com. TestKing.com makes use of Microsoft Exchange Server messaging solution. The TestKing.com network consists of a single ActiveDirectory domain named testking.com. You have received instructions from the CIO to install Exchange Server 2010 that has the followingservers： * Two Edge Transport servers named TESTKING-SR24 and TESTKING-SR25 * Two Hub Transport servers namend TESTKING-SR26 and TESTKING-SR27 However， e-mail massages from the Internet should be delivered to internal recipients， in the case of a single Edge Transport failure. What should you do？（）

• A、The best option is to set up two SRV resource records.
• B、The best option is to set up two mail exchange （MX） records.
• C、The best option is to set up two Remote Domains.
• D、The best option is to set up two EdgeSync Subscriptions.