What does "fateseal N" allow a player to do?

Fateseal N is a keyword action that permits a player to look at the top N cards of an opponent's library and then put any number of those cards on the bottom of that player’s library in any order. This ability offers strategic insight into an opponent's deck and can help manipulate their draws, as the player can decide which cards to keep on top and which ones to move away.

The focus of fateseal is distinctly on the opponent’s library, making the chosen answer accurate. The ability does not grant access to a player’s own cards or both players’ cards, nor does it involve shuffling any cards back. Thus, the other options lack alignment with the specific scope and effect of the fateseal keyword.