Where does “к'о” come from?

к'о (Serbo-Croatian) comes from Serbo-Croatian ка̏о, from Serbo-Croatian ка̏ко, from Proto-Slavic kako, from Proto-Slavic kakъ, from Proto-Balto-Slavic *kōkos.

Ancestry of “к'о”, step by step

StepLanguageWordMeaning
1Serbo-Croatianка̏оas, like
2Serbo-Croatianка̏коhow (in what way)
3Proto-Slavickakohow, in which way
4Proto-Slavickakъof what/which kind
5Proto-Balto-Slavic*kōkos—
Every word from Proto-Balto-Slavic *kōkos →Every word from Proto-Slavic kakъ →Every word from Proto-Slavic kako →