The explanation for the exclusion of answer C can be as follows: 1, 2,4,5 generated 1, 4,5 are not included in the given frequent 3- itemsets, and 1, 2,4,5 cannot be frequent 4- itemsets. All three itemsets that can be decomposed from the other four itemsets are included in the given frequent three itemsets.

However, the premise of this problem is not very clear. For the problem of 1, 3, 4, 5, and 1, 4, 5 do not appear in the given frequent 3- itemsets, they should not be included in the 4- itemsets. This may be limited by the condition of "merger strategy" in the title. I don't know much about "merger strategy". I don't know if it's my knowledge defect or a problem. If I know the answer, I will check and improve it.

But I have been engaged in association rule mining research 10 for many years, and I have read dozens of papers but not hundreds. I really have no impression of the "merger strategy" and feel that the topic is wrong.