DOS, which stands for Disk Operating System, is an operating system that runs from a disk drive. It was one of the earliest operating systems developed for personal computers. DOS became popular in the 1980s and early 1990s, primarily due to its simplicity and compatibility with a wide range of hardware.

Here is a detailed explanation of why the correct answer is option 'A' - Disk Operating System:

1. Disk Operating System (DOS):
DOS is an operating system that is designed to be loaded and run directly from a disk drive, such as a hard disk or floppy disk. It is a single-user, single-tasking operating system that provides a command-line interface for interacting with the computer.

2. Drive Operating System:
The option 'B' - Drive Operating System is not the correct answer. While DOS does operate from a disk drive, it is not specifically designed to manage or control the drive itself. Instead, it is an operating system that utilizes the disk drive to store and execute its files.

3. Durable Operating System:
The option 'C' - Durable Operating System is not the correct answer. The term "durable" refers to the ability of a system to withstand failure or damage. DOS, however, does not possess any specific features or characteristics that make it particularly durable.

4. Divided Operating System:
The option 'D' - Divided Operating System is not the correct answer. DOS is not divided into separate components or modules that perform specific functions. It is a relatively simple operating system that provides basic file management and command execution capabilities.

5. Disk Opaque System:
The option 'E' - Disk Opaque System is not the correct answer. The term "opaque" refers to something that is difficult to understand or see through. DOS, on the other hand, is a relatively transparent operating system that allows users to directly interact with the underlying hardware and software.

In conclusion, the correct answer is option 'A' - Disk Operating System. DOS is an operating system that runs from a disk drive and provides a command-line interface for users to interact with the computer.