If two measurement variables are both found to be changing over time, what does this mean?

It means there is a causal link between the two variables.





It means there is a common cause of the changes in both variables (other than time).





It means that even though the two variables may be highly correlated, they could be completely unrelated in terms of cause and effect.





None of the above.|||It means that even though the two variables may be highly correlated, they could be completely unrelated in terms of cause and effect.