You are employed as the Exchange administrator at Company.com.You are in the process of installing a new Exchange Server 2010 Organization.After the installation you send a text message to an external client and receive the subsequent non-delivery report （NDR）： "Delivery has failed to these recipients or groups： [e-mail] （[e-mail]）.The recipient’s e-mail system isn’t accepting messages now.Please try resending this message later or contact the recipient directly." You attempt to e-mail the user from an external e-mail system with great success.To ensure productivity you need to make sure e-mails can be sent to external clients from within the organization. What should you do？（）

A. Your best option would be to create an MX record.
B. Your best option would be to create a Send connector.
C. Your best option would be to create an SMTP site link.
D. Your best option would be to create an accepted domain.