When BGP tuning is used, how is packet flow into the e-commerce module controlled?（）

A.by tracking the status of objects along the path to the e-commerce module

B.by detecting undesirable conditions along the path to the e-commerce module

C.by using the MED to communicate the site preferences for traffic to multiple ISPs

D.by communicating the available prefixes, routing policies, and preferences of each site to its ISP

E.by moving the SLB to a position where selected traffic to and from the servers does not go through the SLB