Your company’s organization is authoritative for the contoso.com domai.Your network contains a Windows Server 2008 R2 certification authority （CA）.You have an Exchange Server 2010 server named Server1.Server1 has the Client Access， Hub Transport， and Mailbox server roles installed. You plan to create a Federated Sharing relationship between your company and another company named Northwind Traders.Northwind Traders has an internal root CA.You need to install a certificate that can be used to create the federated trust.The solution must minimize costs. What should you do from Server1？（）

A. Generate a self-signed certificate.
B. Request a Computer certificate from the contoso.com CA
Create a computer certificate request and submit the request to a third-party trusted CA
D. Create a computer certificate request and submit the request to the Northwind Traders CA