What happens to the sessions that are currently connected to the database instance?

Your database is open and the listener is running. The DBA stops the listener by using the
command:
LSNRCTL> STOP
What happens to the sessions that are currently connected to the database instance?

A.
They can perform only queries.

B.
They are not affected and continue to function normally.

C.
They are terminated and the active transactions are rolled back.

D.
They are not allowed to perform any operations till the listener is started.