Quiz: Counting Paths Through Centroid

When counting paths of length $k$ through a centroid, you compute distances from the centroid to all nodes. Why must you subtract paths where both endpoints are in the same subtree?

1. A.Those paths do not pass through the centroid, so they are invalid
2. B.Those paths were counted in a previous recursion level
3. C.Those paths are always shorter than $k$
4. D.The centroid node itself is not part of any valid path