What occurs when a second permanent with the world supertype enters the battlefield?

When a second permanent with the world supertype enters the battlefield, all other permanents with that supertype are put into their owner's graveyards. This is a specific rule that applies to permanents with the world supertype, emphasizing its unique nature in gameplay.

The world supertype acts as a restriction; there can never be more than one permanent with this supertype on the battlefield at the same time. So when that second world permanent enters, the game state checks for this condition and enforces it by putting the previously existing world permanent into the graveyard immediately. This ensures that only one world permanent can exist on the battlefield at any time, creating a strategic element when playing with or against such cards.

Understanding the interaction and consequences of the world supertype is crucial for recognizing how it affects game flow and strategy in Magic: The Gathering. The other choices do not accurately reflect the consequences of multiple world permanents entering the battlefield, as they either imply incorrect actions or state-based applications that do not correspond with the rules governing world permanents.