On the surface, this Labor Day holiday caps another dark year for unions and many working-class Americans. -NY Times
I found the meaning of it in the dictionary like the below but I don't know which one is correct.
1.[VERB] [usu passive] [BRIT] If a sports player is capped, they are chosen to represent their country in a team game such as football, rugby, or cricket.
2.[VERB] If the government caps an organization, council, or budget, it limits the amount of money that the organization or council is allowed to spend, or limits the size of the budget.
3.[VERB] [JOURNALISM] If someone says that a good or bad event caps a series of events, they mean it is the final event in the series, and the other events were also good or bad.
4.[VERB] [usu passive] If someone's teeth are capped, covers are fixed over them so that they look better.