Final answer:
A dental assistant can best show empathy by acknowledging their patient's frustrations, listening actively, and offering reassurance to ease their discomfort.
Step-by-step explanation:
The best response for a dental assistant to show empathy to a patient feeling frustrated with their treatment is to acknowledge their feelings, listen actively, and provide reassurance. The dental assistant might say, "I can see this is really tough for you. Can you tell me more about what's been frustrating?" By inviting the patient to share more about their feelings and experiences, the assistant demonstrates understanding and concern. Providing a soothing and empathetic response can help to ease the patient's discomfort and frustration.