Final answer:
The best action is to request a professional interpreter to ensure accurate communication, as this guarantees that medical information is clearly understood by the patient and their family.
Step-by-step explanation:
When dealing with a situation in which a patient's family member, who doesn't speak English, is interpreting and there is concern that the message is not adequately conveyed, the best course of action would be to request the assistance of a professional interpreter to ensure accurate communication (option B). This approach is important to guarantee that all medical information is correctly understood by the patient and their family. While maintaining cultural sensitivity is important (option A), clear understanding in medical settings is critical. Using non-verbal communication (option C) and providing written instructions (option D) can be supportive methods too, but they may not be sufficient if the person does not understand the language in which the information is written, or if the nuances and specific details of the medical information are lost.