What is a valid implicit permit rule for traffic that is traversing the ASA firewall?

What is a valid implicit permit rule for traffic that is traversing the ASA firewall?
A . ARPs in both directions are permitted in transparent mode only.
B . Unicast IPv4 traffic from a higher security interface to a lower security interface is permitted in routed mode only.
C . Unicast IPv6 traffic from a higher security interface to a lower security interface is permitted in transparent mode only.
D . Only BPDUs from a higher security interface to a lower security interface are permitted in transparent mode.
E . Only BPDUs from a higher security interface to a lower security interface are permitted in routed mode.

View Answer

Answer: A

Explanation:

ARPs are allowed through the transparent firewall in both directions without an ACL. ARP traffic can be controlled by ARP inspection.

Source: http://www.cisco.com/c/en/us/td/docs/security/asa/asa93/configuration/general/asa­general-cli/intro- fw.html