Which word best replaces "invariably" in the sentence regarding Anna's punctuality?

The word "invariably" means without variation or consistently. In the context of the sentence about Anna's punctuality, the best replacement would be a word that conveys the same sense of being regular and unchanging. "Constantly" fits this definition perfectly, as it implies that Anna is consistently punctual without fail.

On the other hand, "never," "rarely," and "occasionally" convey a sense of infrequency or lack of consistency, which does not align with the intended meaning of "invariably." Therefore, "constantly" is the most accurate synonym, as it emphasizes the idea of Anna being reliably punctual at all times.