In the context of Game Theory, which of the following best describes a subgame perfect equilibrium?

A subgame perfect equilibrium is a concept in game theory that describes a situation where players make the best possible decisions at every point in the game, not just at the beginning. This means that even if the game changes or a player has to make a decision later on, they will still choose the best strategy based on what has happened so far. For example, imagine two players in a game where they take turns to choose actions. If at any turn, a player can choose a strategy that will lead to the best outcome for them, even considering future moves, then they are following a subgame perfect equilibrium. This concept helps ensure that players are acting rationally throughout the entire game, making it a key idea in understanding strategic interactions.