What defines a player as a 'runner' in football?

A player is defined as a 'runner' in football primarily when they have possession of the ball and are attempting to advance it towards the opposing team's end zone. The correct understanding involves recognizing that a runner is any player who has possession of the ball, regardless of how they obtained it, including through a handoff, a pass, or recovering a fumble.

The option regarding simulating possession of a live ball is misleading because it does not align with the actual rules. A player does not become a runner by merely pretending to have the ball; possession must be legitimate according to the rules of play.

In contrast, receiving a lateral pass or running towards the end zone can certainly involve a player as a runner. However, simply receiving a lateral or moving in a specific direction does not automatically designate one as a runner. The term 'runner' specifically refers to the player having true possession of the football and actively trying to advance it. Consequently, possession of the ball is key in defining a player as a runner in football.