What is a valid reason for a switch to deny port access to new devices when port security is enabled?

What is a valid reason for a switch to deny port access to new devices when port security is
enabled?

A.
The denied MAC addresses have already been learned or configured on another secure
interface in the same VLAN.

B.
The denied MAC addresses are statically configured on the port.

C.
The minimum MAC threshold has been reached.

D.
The absolute aging times for the denied MAC addresses have expired.