A Cat Continually Comes to Xavier's Back Door,so He Decides

A cat continually comes to Xavier's back door,so he decides to keep it.Which of the following is true?

A) If the cat belongs to someone else,Xavier has no property rights.
B) Xavier has property rights as long as the cat doesn't have any tags.
C) If the cat belongs to someone else,Xavier has rights over the cat effective against everyone but the original owner.
D) Xavier has rights over the cat under the rule of finders keepers,losers weepers.
E) Xavier cannot have property rights over a living thing.