understand Diff Formatting --cc flag?

understand Diff Formatting --cc flag?

hi,

  It is really too hard to understand Diff Formatting --cc flag.

  It is hard to understand"...hunks whose contents in the parents have
only two variants..".

  My question is:
   1)what does "variant" mean here?
   2)what about all the other cases? 0 variants, 1 variants, and 3
variants and even more?

   3)Can I understand "--cc" as simply as: "--cc lists only hunks
which were modified from all parents."


  Any comments, hinits are welcome!  Thank you in advance!


//---------------------------------------------------------------------
Here is the help from the command: git help log

   Diff Formatting
       Listed below are options that control the formatting of diff
output. Some of them are specific to git-rev-list(1), however other
diff options may be given. See git-diff-files(1) for more options.

       -c
           With this option, diff output for a merge commit shows the
differences from each of the parents to the merge result
simultaneously instead of showing pairwise diff between a parent and
the
           result one at a time. Furthermore, it lists only files
which were modified from all parents.

       --cc
           This flag implies the -c option and further compresses the
patch output by omitting uninteresting hunks whose contents in the
parents have only two variants and the merge result picks one of
           them without modification.

       -m
           This flag makes the merge commits show the full diff like
regular commits; for each merge parent, a separate log entry and diff
is generated. An exception is that only diff against the first
           parent is shown when --first-parent option is given; in
that case, the output represents the changes the merge brought into
the then-current branch.