Can an assistant referee enter the field of play to help check if the defenders' wall is 10 yards from the ball?

An assistant referee can enter the field of play to help check the distance between the defenders' wall and the ball, provided that the referee is aware of their presence on the field. This situation arises from the assistant referee's role in supporting the main referee and ensuring that the rules regarding the distance for free kicks are enforced correctly. It's crucial that the assistant referee communicates with the referee to maintain the flow of the game and to make sure that all actions taken are within the context of the match.

Entering the field in this scenario helps achieve better accuracy regarding the enforcement of the Laws of the Game, particularly regarding the positioning of the wall during a free kick. Each official on the field is responsible for ensuring the game is played fairly and according to the rules, and this collaboration shows the teamwork necessary among officials.

The other choices present scenarios that limit the assistant referee's ability to assist effectively. Remaining outside the field would hinder their ability to assess the situation directly, while only allowing entry during halftime or if play has stopped would not serve the immediate need to enforce the distance rules effectively during active play. Thus, being aware and coordinating movement with the referee allows for better management of the game.