Strange Program appears... (Nautilus appears in KDE enviroment from its own)

I don’t know where it come from i didn’t download any file managers , my distro was working perfect but 2day when i choose show folder on my bittorrent client , it opens folder through a strange program i don’t knw where it come from and i need to remove it , how can i do so ?
before i have this problem everything was fine , when i choose show file/folder it opens with Dolphin but not anymore, however dolphin still working when i choose it from programs list

update : i kept it open and then opened my system activity and i found its name > nautilus , is it installed by default ? and why it appeared from its own ? and how to remove it

My guess is that it was installed as a dependency for an application. (for example dropbox has nautilus as dependency).
You could try removing it and see which applications gets removed also. This is most likely than the culprit who brought in nautilus.

As for a workaround there is always the possibility to link /usr/bin/dolphin to /usr/bin/nautilus

or to save any despondencies issues - don’t UN-install it just make dolphin the default application again

found in the menu (Click the netrunner [start - damn wot to call in in linux] icon) - settings - system settings you can then set Dolphin back as default. See if that cures it