Ask which one out of many
どれ is the question word for asking "which one" out of three or more things.
JLPTN5
どれ = which one?dore ga ~ desu ka
Which one is [description]?
Example Sentence

Which hat is yours?
Use どれ on its own to ask the listener to pick one item from a group of three or more. It stands alone like a noun and does not attach directly to another noun. To ask "which" while naming the noun, use どの instead, and remember that for a choice between just two things Japanese uses どっち.