why would you use vah instead of yah here?
You can use both. They would both mean "She is a woman".
However, be careful as yah is only used when the person is close to you or you're pointing at him (her, in this case). So in most cases, we end up using vah more.
In my Hindi class I learned that because someone you are writing about is never right there (on the page I suppose), you always use the far versions of he/she/it/they (वह/वे). My teacher always told us you really only use यह in speaking.
Shouldn't it be "woh" or "voh" instead "vah"?
Both can be used, Vah and voh. Vah is more theoretically correct. (Like ancient Hindi)
I had the correct answer but it said it was incorrect even though it was word for word the same as their correct answer
It sounds like the word order is incorrect in that sense. You cant use exact translation from english. English would be "she is a woman" but in Hindi it would be "she a woman is." Hope that helps.
Vah ek aurat hai