Which of the following are benefits of VLANs?（）

• A、They increase the size of collision domains.
• B、They allow logical grouping of users by function.
• C、They can enhance network security,
• D、The increase the size of broadcast domains while decreasing the number of the broadcast domains.
• E、The increase the number of broadcast domains while decreasing the size of the broadcast domains.
• F、They simplify switch administration.