Hi shibsriz,

This SC includes a very specific verb issue (one that you will see at least once on Test Day, so it's worth knowing).

The sentence refers to a (current) religion that holds ceremonies on specific days of each century. Since it's a religion that exists right now (the word "holds" provides THAT clue), we know that the religion probably has some planned events for this century and will end up having more ceremonies into the next century (and beyond).

"Differed" is a past tense verb; while it can refer to past ceremonies, it's not the correct verb for present (or future) ceremonies. For those, we need a "timeless" verb - a verb that ends in "-ing." Here, the verb "differing" is correct.

GMAT assassins aren't born, they're made,
Rich