An engineer must configure an ACL that permits packets which include an ACK in the TCP header. Which entry must be included in the ACL?
A. access-list 110 permit tcp any any eq 21 tcp-ack
B. access-list 10 permit tcp any any eq 21 established
C. access-list 110 permit tcp any any eq 21 established
D. access-list 10 permit ip any any eq 21 tcp-ack