What action results in a 5-yard penalty due to a player entering or leaving the game incorrectly?

The correct action that results in a 5-yard penalty due to a player entering or leaving the game incorrectly is illegal substitution. In football, a team must adhere to specific rules regarding player substitutions. If a player attempts to enter or leave the field of play while the ball is in play, or if there are too many players on the field at the snap, this constitutes an illegal substitution. The penalty for this infraction is a 5-yard mark-off against the offending team as it disrupts the flow of play and can create an unfair advantage.

This rule is important as it emphasizes the need for teams to communicate effectively and maintain proper control during substitutions, ensuring that all players are on the same page. Other situations such as a false start, encroachment, or delay of game involve different aspects of gameplay and have their specific penalties, but they do not pertain to the improper entry or exit of players, which is why illegal substitution is the appropriate answer in this context.