What action should you be prepared to take when verifying a security solution？（）

A. having alternative addressing and VLAN schemes
B. having a rollback plan in case of unwanted or unexpected results
C. running a test script against all possible security threats to insure that the solution will mitigate all potential threats
D. isolating and testing each security domain individually to insure that the security design will meet overall requirements when placed into production as an entire system