Kaun-sā/sī/se कौन-सा/सी/से (which one) is an interesting word in H/U. Kaun कौन is the only interrogative which allows suffixation with the adjectival sā/se/sī सा/सी/से to form a selective interrogatives ("which one" in English).1/n

Further this 'definiteness' added to Hindi "Kaun-sā/sī/se" & English "which one" makes them eligible for use for both animate & inanimate objects e.g. kaun-si sāṛī कौन-सी साड़ी vs kaun-sā laṛkā कौन -सा लड़का. Or English "which one of those boys / umbrellas" 2/n

Note that this -sā -सा suffix agrees in number & gender with the following noun. Although kaun कौन alone is used only in singular & for animate e.g. kaun gayā? कौन गया ? Its inanimate counter part is kyā क्या e.g. kyā huā क्या हुआ. 3/end

Another interesting thread on Definiteness marking in Bhojpuri language. https://twitter.com/avtansa/status/1119348091575046144?s=19