You created a profile APP_USER and assigned it to the users. After a month， you decide to drop theprofile.Some user sessions are currently connected to the database instance and are using the APP_USERprofile. This command is used to drop the profile： SQL> DROP PROFILE app_user；  Which statement describes the result（）

• A、The command produces an error.
• B、The profile is dropped and current user sessions use the DEFAULT profile immediately.
• C、The profile is dropped and only the subsequent user sessions use the DEFAULT profile.
• D、The profile is dropped， the sessions are terminated， and the subsequent user sessions use theDEFAULT profile.