To answer this question, you need to understand the different types of Job Entry Subsystems (JES) in mainframe systems. Let's go through each option to understand why it is correct or incorrect:
Option A) JES1 - This option is incorrect because JES1 is not a valid type of JES. JES1 does not exist as a separate subsystem in mainframe systems.
Option B) JES2 - This option is correct. JES2 is one of the types of Job Entry Subsystems (JES) in mainframe systems. It is responsible for managing the submission and execution of batch jobs.
Option C) JES3 - This option is correct. JES3 is another type of Job Entry Subsystem (JES) in mainframe systems. It provides advanced features for job management, such as job routing and workload balancing.
Option D) JES4 - This option is incorrect because JES4 is not a valid type of JES. JES4 does not exist as a separate subsystem in mainframe systems.
The correct answer is B, C. These options are correct because JES2 and JES3 are valid types of Job Entry Subsystems (JES) in mainframe systems.