The correct answer is option (A):
opportune
The correct answer is "belated" because the word "tardy" means arriving or done late, delayed, or slow in doing something. "Belated" directly reflects this meaning, as it also signifies something happening later than expected or the proper time. While "overdue" also suggests lateness, it often implies a deadline or specific expectation has been missed, whereas "tardy" can be a more general descriptor of being late. "Slow" and "opportune" are not synonyms for "tardy". "Slow" describes the pace of something, and "opportune" means happening at a good or suitable time. Therefore, "belated" is the most accurate synonym for "tardy" among the given choices.