There are three implementations of CAC. Which of the following statements about the implementation of CAC based on channel utilization is wrong?

There are three implementations of CAC. Which of the following statements about the implementation of CAC based on channel utilization is wrong?
A . When the AP receives a new user online request, it first calculates the channel utilization rate on the current radio, and if the new user threshold is not reached, the new user is allowed to go online
B. If the channel utilization reaches the new user threshold after the new user goes online, the access request of other new users is rejected and an alarm is sent, but the SSID cannot be hidden
C. For the access of roaming users, check whether the channel utilization rate has reached the roaming user threshold. If it reaches, then reject the roaming user’s access request and send an alarm
D. The AP periodically checks the channel utilization of the radio frequency, and once it drops below the threshold for new users, it sends a release alarm to allow new users to go online

Answer: B