The correct answer is: B. 6.2
In DOS 6.2, the CHKDSK command was changed to SCANDISK. This was done to improve the functionality of the command and to make it more user-friendly. SCANDISK can now check for and fix a wider range of disk errors, and it also includes a graphical user interface that makes it easier to use.
Option A is incorrect because CHKDSK was not changed to SCANDISK in DOS 5.0. In DOS 5.0, CHKDSK was a command-line tool that could be used to check the integrity of a disk and to fix any errors that were found.
Option C is incorrect because CHKDSK was not changed to SCANDISK in DOS 6.0. In DOS 6.0, CHKDSK was still a command-line tool, but it had been improved to include some new features, such as the ability to check for bad sectors on a disk.
Option D is incorrect because CHKDSK was not changed to SCANDISK in DOS 6.2. In DOS 6.2, CHKDSK was changed to SCANDISK, which is a more powerful and user-friendly tool.