Error on 2014 NFHS test

[WestCoaster]

So this rule only pertains to a running play such as that following an interception, possession of a kick etc. It seems impossible then to have a run play from scrimmage where this rule applies, since the fumble occurs in the end zone which by definition is a loose ball play.

Thank you all for the clarification. It's important to me that I understand this rule clearly. I've actually had this play in a youth game and enforced the horse collar penalty (incorrectly) from the goal line. I will get it right next time.