Dora, who was eight years old, went to the grocery store with her mother. Dora pushed the grocery cart while her mother put items into it. Dora's mother remained near Dora at all times. Peterson, another customer in the store, noticed Dora pushing the cart in a manner that caused Peterson no concern. A short time later, the cart Dora was pushing struck Peterson in the knee, inflicting serious injury. If Peterson brings an action, based on negligence, against Dora, Dora's best argument in defense would be that 
Dora exercised care commensurate with her age, intelligence, and experience.  Dora is not subject to tort liability. Dora was subject to parental supervision. Peterson assumed the risk that Dora might hit Peterson with the cart.