4
Pretty sure it’s the rule that was put in place after the raiders holy roller
i mean otherwise you could "fumble" past the line of scrimmage and as long as it goes forward and isnt scooped and ran by defense theres no downside
You can’t already purposely fumble though right? Otherwise people would just do that on earlier downs to push the ball a few more yards
right but on 4th even if the other team recovers it ur giving the ball away regardless so its less risky