What is the standard function of an access control portal?

The standard function of an access control portal is to ensure that only authorized users are granted access to a particular area while allowing free egress, or exit, for individuals. This is critical in maintaining security within a facility by restricting entry to only those who have been verified, such as employees or authorized personnel.

By allowing free egress, the system ensures that once access is granted, individuals can exit without restriction, which can be essential for safety during emergencies. Access control portals are designed to balance security with the need for individuals to move freely once they are deemed authorized to enter a space.

While requiring biometric verification can be part of a more advanced access control system, it's not a standard function of all access control portals. Similarly, preventing egress would contradict the notion of allowing individuals to leave an area freely once they have gained entry. Thus, the correct answer encapsulates both the security aspect of controlled access and the necessity of allowing individuals to exit unimpeded.