I suppose this will depend on your ls implementation but on my LMDE (basically, Debian testing) I have:
$ man ls | grep -- '-1' across -x, commas -m, horizontal -x, long -l, single-column -1, -1 list one file per line As well as (yes, it's the same output)
$ ls --help | grep -- '-1' across -x, commas -m, horizontal -x, long -l, single-column -1, -1 list one file per line