A controlled area where an even greater degree of security is required is called:

A limited area is a controlled zone within a facility where a higher level of security is required than in general access areas. These are typically used to protect sensitive operations or assets. Access is restricted to authorized individuals who require entry for specific operational duties.

Pass system area (B) refers to the access control method, not the area classification.

Multiple areas (C) and External area (D) are not specific security designations.