The correct answer is B. MEM.
MEM is a command-line utility that displays information about the amount of physical and virtual memory available on a computer. It can also be used to configure memory usage.
EMM is a memory manager that was used in MS-DOS to expand the amount of available memory. It is no longer necessary in modern operating systems.
CHKDSK is a command-line utility that checks the integrity of a disk and can also be used to fix errors. It does not provide information about memory usage.
MEMMAKER is a memory management utility that was used in MS-DOS to optimize memory usage. It is no longer necessary in modern operating systems.
None of the above is the correct answer.