What is the rarest unicorn in the world?

Excuse me, could you please elaborate on what you mean by the "rarest unicorn in the world"? Are you referring to a mythical creature or is there a specific species of unicorn that is known to be the most scarce among its kind? If you're indeed asking about a real-life creature, perhaps you're alluding to a rare breed of horse or another animal that shares some characteristics with the legendary unicorn. Could you clarify your question for me?