Final answer:
The nurse demonstrates the ethical principle of veracity by option a, where all relevant information about a patient's medical condition is disclosed to their family, ensuring transparency.
Step-by-step explanation:
The ethical principle of veracity involves telling the truth and providing accurate information to patients about their condition and care. In the scenarios presented, the nurse demonstrates veracity by disclosing all relevant information about a patient's medical condition to their family (option a), ensuring transparency and honesty. Withholding information (option b) or exaggerating the benefits of a treatment (option c) does not align with the principle of veracity. Respecting a patient's request not to be informed (option d) may be related to the principle of autonomy but does not reflect veracity if the patient is unaware of the potential risks involved. Professional health care must adhere to ethical principles ensuring informed consent, respect for patient rights, and honest communication.