Final answer:
Device drivers provide a uniform interface between the I/O subsystem and hardware devices, similar to how system calls interface between applications and the OS. They are essential for hardware communication and are specific to both the operating system and the hardware.
Step-by-step explanation:
The correct answer to the question is c) Device drivers. Device drivers present a uniform device-access interface to the I/O subsystem, much like system calls provide a standard interface between the application and the operating system. These drivers are specialized programs that allow higher-level computer programs to interact with a hardware device. Whenever a calling program invokes a routine in the driver, the driver issues commands to the device. Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware-dependent and operating-system-specific, ensuring that every device has a driver that allows it to communicate effectively with the system.