Passwords must be changed at least once every 60 days (depending on your environment).
Password aging or expiration must be enforced on all systems. Upon password expiration,
if the password is not changed, only three grace logins must be allowed then the
account must be disable until reset by an administrator or the help desk. Password
reuse is not allowed (rotating passwords).

The correct answer is Trap door. Answer view refers to a mechanism in a database system that restricts access to certain information within the database. The view implements the principle of least privilege.
Answer Open door is a distracter, and answer Data diode refers to a mechanism usually in multilevel security systems that limits the flow of classified information to one direction.

The correct answer is "Operates at Layer 3, the Network Layer". A bridge operates at Layer 2 and therefore does not use IP addressing to make routing decisions.

Reference: pg 489 Shon Harris