When are state-based actions checked?

State-based actions are checked whenever a player would receive priority. This occurs predominantly after spells and abilities resolve and before any player can take actions. During this check, the game evaluates the current state of the battlefield and determines if any state-based actions need to be taken, such as removing creatures with zero toughness or placing a token into a player's graveyard due to the effects of another spell or ability.

This ensures that any necessary game actions are addressed before players are given the opportunity to cast spells or activate abilities. The timing is crucial because it allows for the most accurate representation of the game state before players make decisions or carry out further actions.

The other options suggest instances where state-based actions are not monitored. Spells resolving or a creature attacking don't inherently trigger a state-based action check; these situations primarily relate to combat or casting spells rather than the comprehensive state evaluation of the game. Additionally, the end of each turn is more about the turn structure rather than the specific timing for checking state-based actions, which focus on player priority moments.