When the alien being has the capability to do things on its own when multiple options are available in the context of the environment in which it is operating , the existence of its free will can be established.
Animals are instinct-based and their behavior is predictable. But they do have a limited free will which they can exercise on their own volition just like a cow tethered to a Peg. Thus predictability and free-will can go together as well.
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