What criteria must be met for a throw-in to be valid?

A valid throw-in must adhere to specific criteria to ensure that it is executed properly and according to the Laws of the Game. The only correct criteria for a valid throw-in highlight that the throw must be performed with both hands simultaneously, starting from behind the player's head, and both feet must remain on the ground during the throw. This ensures that the throw is executed in a controlled manner and is fair to both teams, preventing any advantage gained from an improper throw.

The requirement for both feet to remain on the ground prevents players from gaining extra height or momentum that could potentially interfere with fair play. Furthermore, starting the throw from behind the head and using both hands ensures that the ball is thrown clearly and accurately into play, maintaining the flow of the game.

This aligns with the Laws of the Game specified by FIFA and is crucial for maintaining consistency in officiating during matches. While other options mentioned certain aspects related to throw-ins, they do not meet the complete and accurate criteria necessary for a valid throw-in.