What is the purpose of an explicit "deny any" statement at the end of an ACL？（）

A.none，since it is implicit
B.to enable Cisco IOS IPS to work properly；however，it is the deny all traffic entry that is actually required
C.to enable Cisco IOS Firewall to work properly；however，it is the deny all traffic entry that is actually required
D.to allow the log option to be used to log any matches
E.to prevent sync flood attacks
F.to prevent half-opened TCP connections