누구 (nugu) = who
remember the topic marker and subject marker particles?
네, 맞아요
subjec marker particle = 이(i) / 가(ga)
topic marker particle = 은(eun) / 는(neun)
when u ask a simple question like who did something you need to use the subject marker
we used 가 (ga) for 누구 (nugu)
누구 (nugu) = who
