To answer this question, you need to understand the command used to find the block size on a Unix file system.
Option A) blksz - This option is incorrect because there is no such command "blksz" to find the block size on a Unix file system.
Option B) szblk - This option is incorrect because there is no such command "szblk" to find the block size on a Unix file system.
Option C) cmchk - This option is correct because the "cmchk" command is used to find the block size on a Unix file system. This command can be used to check the block size of a file system or a device.
Option D) chksz - This option is incorrect because there is no such command "chksz" to find the block size on a Unix file system.
The correct answer is Option C) cmchk. This option is correct because the "cmchk" command is used to find the block size on a Unix file system.