Final answer:
If a patient becomes violent in a patient / provider relationship, the provider should immediately retreat to a safe location if possible. Taking any weapon away from the patient and calling for law enforcement is also recommended.
Step-by-step explanation:
If you establish a patient / provider relationship and the patient becomes violent, you should immediately retreat to a safe location if possible (option C). This is the best course of action to ensure your safety and the safety of others. Engaging in physical combat with the patient (option A) or using restraint devices (option B) can escalate the situation and potentially cause harm. Taking any weapon away from the patient and calling for law enforcement (option D) is also an appropriate response to ensure the safety of everyone involved.