The correct answer is: A. Conventional Memory
Conventional memory is the first 640 kilobytes (KB) of a PC’s memory. It is used by the operating system and other essential programs. Upper memory blocks (UMBs) are a type of memory that can be used by programs that do not fit in conventional memory. They are located in the first 1 megabyte (MB) of memory, above the 640 KB limit of conventional memory.
Extended memory is the memory that is above 1 MB. It is not directly accessible by the CPU, but it can be used by programs through the use of a memory manager such as EMM386.
Expanded memory is a type of memory that is used to expand conventional memory. It is not directly accessible by the CPU, but it can be used by programs through the use of a memory manager such as QEMM.
Reserved memory is memory that is reserved for use by the operating system and other essential programs. It is not available for use by other programs.
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