The database users are connecting to the PROD database from different applications， thereby degrading the database performance. The senior database administrator suspects the large number of concurrent connections to be the reason for low performance and asks you to restrict the number concurrent connections per database user to one. Which action would you take to achieve this objective？（）

A. set the SESSIONS to 1 in the parameter file
B. grant SINGLE SESSION privilege to all of the users
C. set the SESSIONS_PER_USER to 1 in the users’ profile
D. grant RESTRICTED SESSION privilege to all of the database users
E. create a role with SINGLE SESSION privilege and assign the role to the user