What is a potential weakness of this solution?

A network administrator wants to implement MAC filtering for the wireless network of a local financial firm to ensure that only employees can access the wireless network.

What is a potential weakness of this solution?
A . MAC filters cannot be applied with WPA2 encryption.
B . Authorized MAC addresses are visible in plaintext in the air and can be easily spoofed.
C . Many popular clients do not have the capability to connect to WLANs that use MAC filters.
D . MAC filters offer no protection against authorized users who try to connect unauthorized devices.

Answer: D