Answer:
B. A doctor tells a nurse at lunch about a patient’s medical condition.
Step-by-step explanation:
It's ok for doctors to disclose the medical condition and even diagnosis of a patient with the nurse who is currently assisting, but only because it's important for that nurse to know what's going on so they can provide the most effective care possible. If they are at lunch however, that means they're on break, they're not in the privacy of the patient's room, and they're most likely going to be in earshot of other people.
Hope this helps :)