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.