The answer would be sequence.
-It cannot be cause and effect because time does not really matter when you are dealing with cause and effect, all that matters is that this happened and it made this happen.
-It cannot be problem and solution because problem and solution is just about explaining the problem and finding/explaining the solution.
-It cannot be compare and contrast because compare and contrast is just about finding comparisons between two or more subjects and contrasts between the same subjects.
-And sequence tells events in the order they happen in time.
