While working with which command is used to copy all files from the currently logged drive and directory with the extension .txt to the drive a

To copy all files from the currently logged drive and directory with the extension .txt to drive A in MS-DOS, you would use the copy command with the appropriate syntax. Here’s the explanation for each option:
Option A: Copy a. *.txt is incorrect syntax. It does not correctly specify the destination drive.
Option B: Copy *.txt a: copies all files with the extension .txt from the current directory to drive A.
Option C: Copy *.txt c: attempts to copy .txt files to drive C, not drive A.
Option D: Copy *.txt all.txt attempts to copy .txt files to a file named all.txt, not to a specific drive.

Therefore, Option B is the correct command to copy all files with the extension .txt from the current directory to drive A in MS-DOS.