In which cases is reference partitioning effective in enhancing performance？（）
- A It is effective only in partition pruning.
- B It is effective only in partitionwise joins provided that the query predicates are different from the partitioning key.
- C It is effective in both partition pruning as well as partitionwise joins provided that the query predicates are identical to the partitioning key.
- D It is effective in both partition pruning as well as partitionwise joins irrespective of whether the query predicates are different from or identical to the partitioning key.