To answer this question, you need to understand how a job can send a status message to a TSO (Time Sharing Option) user at its completion.
Option A) STATUS - This option is incorrect. The STATUS command is used to display the status of a job or a job step, but it does not send a status message to a TSO user.
Option B) NOTIFY - This option is correct. The NOTIFY parameter is used in the job control language (JCL) to specify a user or a group of users to be notified when the job completes. The message is sent to the TSO user's message queue.
Option C) ENDMSG - This option is incorrect. The ENDMSG parameter is used in JCL to specify whether or not to send a completion message to the job's initiator. It does not send a status message to a TSO user.
Option D) USER - This option is incorrect. The USER parameter is used in JCL to specify the user ID that the job should run under. It does not send a status message to a TSO user.
The correct answer is B) NOTIFY. This option is correct because the NOTIFY parameter in JCL is used to send a status message to a TSO user at the completion of a job.