Hi! I think the answer is B. Relationships, The definition of the word is "<span>the way in which two or more concepts, objects, or people are connected or the state of being connected" which means they have something in common? (Sorry if it's wrong, tried my best) -Queenb369</span>
Its orbit, if it does not orbit like the other planets (around the sun) it cant be a planet, thats why pluto isnt a planet because its orbit was incorrect.