What duty was breached if a player is injured while a coach is on the phone during practice?

The duty that is breached in this scenario is related to supervision. Coaches have the responsibility to provide a safe environment and ensure that all players are monitored during practice. This includes being attentive to the players' activities and being available to respond to any incidents or injuries that may occur.

When a coach is on the phone, they are distracted and cannot properly oversee the practice, which increases the risk of injury for the players. The role of supervision involves not only overseeing drills and activities but also being able to promptly address any emergencies or safety concerns. Hence, failing to supervise adequately while being distracted signifies a breach of that duty.

In this case, the other options, while relevant to coaching responsibilities, do not encompass the immediate oversight and attentiveness required to ensure player safety during practice. Proper teaching, injury evaluation, and planning are all essential, but they do not directly address the critical need for a coach to be present and vigilant during physical activities.