As we all know, correlation does not imply causation. On other words, if X and Y are correlated, it doesn't necessarily mean that X causes Y; there are two other possible explanations. What are they? Take two of these three explanations for the correlation between X and Y and, using an example, show that these two explanations do not have to be mutually exclusive. In other words, give an example of an X and Y that are related in, simultaneously, two different ways.