Final answer:
Dr. Livesey saves the captain's life likely because of his duty and ethical responsibility as a conscientious doctor.
Step-by-step explanation:
The question refers to a scenario in which Dr. Livesey saves the captain's life. The multiple choice options suggest different motivations for Dr. Livesey's actions, ranging from respect for the captain to a request for help to his professional duty as a doctor. The most likely answer from the given options is that he is a conscientious doctor. Dr. Livesey's character is often portrayed as ethical and dedicated to his medical profession, suggesting that his actions are guided by his responsibility to care for the sick and injured regardless of the circumstances.