The irony in the ending of the story is that Jack believed he was tidying up his kitchen, but instead, his efforts resulted in a messier kitchen than when he started. This suggests that despite his intentions to clean and organize, he failed to achieve his goal, which contrasts with the typical expectation that tidying would lead to a cleaner space. Therefore, the correct answer would be:
Jack decided his kitchen was clean enough even though it was messier than when he had started to tidy it.