Final answer:
The most beneficial action for a heart attack victim is to call emergency services, as immediate medical attention is critical. Other actions, like deep breathing or resting, do not substitute for professional medical intervention.
Step-by-step explanation:
The most beneficial action for a heart attack victim is C) Calling Emergency Services. Immediate medical attention is crucial during a heart attack to provide the necessary treatment and to minimize heart damage. While other actions such as taking deep breaths or resting in a comfortable position may provide temporary relief, they cannot replace the medical intervention provided by professional emergency services. In a situation where the heart stops, cardiopulmonary resuscitation (CPR) may be required to maintain blood flow until the heart can be restarted. This involves applying pressure to the chest at a specific rhythm, as outlined in CPR techniques. However, for a person experiencing a heart attack and still conscious, the priority is to get professional help immediately.