Nā is the plural noun marker (what we would call a definite article). Wahine is one of a small handful of words that has a different form in the plural as well. Specifically, the vowel is lengthened: ka wahine, nā wāhine
yeah but after I got it correct it told me that another correct answer is "the woman". I think this needs to be fixed. Luckily, I'm going to the Hawaiian course launch event so maybe I'll ask them there.