How does a zone-based firewall implementation handle traffic between interfaces in the same zone?

How does a zone-based firewall implementation handle traffic between interfaces in the same zone?
A . Traffic between two interfaces in the same zone is allowed by default.
B . Traffic between interfaces in the same zone is blocked unless you configure the same-security permit command.
C . Traffic between interfaces in the same zone is always blocked.
D . Traffic between interfaces in the same zone is blocked unless you apply a service policy to the zone pair.

Answer: A