We can define a correlation as a type of association between two variables. There can be a positive, a negative or no correlation between two variables.
A correlation is a condition for causation, but correlation does not imply any definite causation.
Hence, the answer here is option D : d may cause f.
Explanation: Strong correlation doesn't always mean causation. For example, there is correlation between time and distance. Time doesn't cause the distance. If time added, the distance is much longer. From the example above, correlation doesn't always mean causation. But for any other example, like, heat has strong correlation with ice melts. The heat is the cause for ice to melt, This correlation might be causation.
