You work as the enterprise exchange administrator at Company.com.The Company.com network consists of a single Active Directory domain named Company.com.Company.com has an Exchange Server 2010 organization.the Company.com contains an exchange server 2010 client access server named -ex16 that is accessible via the internet with the following： mail.Company.com or autodiscover.Company.com.during the course of the day you receive an instruction from the cio to ensure that the mobile users is able to make use of auto discover on the internet.What should you do？（）

• A、The best option is to set the external URL for Microsoft-Server-ActiveSync to $NULL.
• B、The best option is to set the external URL for Microsoft-Server-ActiveSync to https：// ExamWays-ex16.com/Microsoft - Server - ActiveSync.
• C、The best option is to set the external URL for Microsoft-Server-ActiveSync to https：//mail. Company.com/Microsoft- Server- ActiveSync.
• D、The best option is to set the external URL for Microsoft-Server-ActiveSync to http：//autodiscover. Company.com/Microsoft- Server- ActiveSync.