Must a player reveal the cards they searched for?

In Magic: The Gathering, when a player searches their library, the general rule is that they are not required to reveal the cards they searched for unless specifically instructed to do so by an effect or ability. This maintains a level of strategic depth, allowing players to keep their choices private unless a particular game situation mandates transparency.

The Comprehensive Rules outline that revealing cards is only necessary when explicitly stated by an ability or game effect. For instance, if a card or effect requires the player to reveal what they have searched for, then they must do so; otherwise, they can keep this information secret from their opponent. This aspect of the game allows players to maintain some control over their strategy and the information shared with their opponent.

The other alternatives lack clarity or misinterpret the conditions under which revealing searched cards is mandated, which clarifies why the outlined choice is the most accurate response to the question.