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.Company.com has headquarters in London and branch offices around the globe.the branch offices of.com are linked to the London offices with one ip site link.all offices of .com is configured as a separate active directory site.all the active directory site of Company.com contains an exchange server 2010 mailbox server and an exchange server 2010 hub transport server.you have received instructions from the cio to make sure that the e- mail sent between the active directory sites is routed through the hubtransport servers in the London offices. What should you do？（）

A. The best option is to change the Exchange-specific site link costs by using the Exchange Management Shell.
B. The best option is to change the site link costs by using the Active Directory Sites and Services.
C. The best option is to get rid of the IP site links and create new SMTP site links by using the Active Directory Sites and Services.
D. The best option is to setting up the main office site as a hub site by using the Exchange Management Shell.