An engineer is upgrading a company's main site to include a connection to a second ISP. The company will receive full Internet routing tables from both ISPs viaBGP. The engineer must ensure that the company does not become a transit autonomous system. Which solution should be included in this design?

A. Tag incoming routes from both ISPs with BGP community no-export. B. Lower the MED for updates sent to the secondary ISP. C. Use a route-map to prevent all prefixes from being advertised to either ISP. D. Modify the local-preference for routes incoming from the primary ISP.