Once a triggered ability is placed on the stack, who is responsible for resolving it?

The correct answer is that the controller of the ability is responsible for resolving it. Triggered abilities are placed on the stack once their conditions are met, but it is the player who controls that ability who has the obligation to resolve it. This means that whenever a triggered ability activates, it remains under the control of the player who triggered it, and that player must carry out the resolution of the effects outlined in the ability when it resolves.

This understanding is rooted in the fundamental principles of how triggered abilities interact with the stack in Magic: The Gathering. The controller of the ability will determine how it resolves in conjunction with any targets or choices outlined in the ability. The options where other players might have a say in resolution generally do not apply to resolving triggered abilities—they cannot intervene to affect how the ability resolves unless prompted by the game rules or situations specifically allowing for such interactions.

In summary, as the controller of a triggered ability, that player has the responsibility to ensure that the ability resolves appropriately, which plays a key role in turn order and game state management during play. This is essential for maintaining a clear process during gameplay and ensuring the structure of resolution reinforces strategic decision-making.