You have an enterprise subordinate certification authority （CA）. The CA issues smart card logon certificates. Users are required to log on to the domain by using a smart card. Your company’s corporate security policy states that when an employee resigns， his ability to log on to the network must be immediately revoked. An employee resigns. You need to immediately prevent the employee from logging on to the domain. What should you do（）
- ARevoke the employee’s smart card certificate.
- BDisable the employee’s Active Directory account.
- CPublish a new delta certificate revocation list （CRL）.
- DReset the password for the employee’s Active Directory account.