exposure to sea air a nutritional deficiency a microorganism lack of exercise
I gave my students this multiple choice question: Scurvy is a disease that sailors often got on long voyages. It was discovered that scurvy could be prevented by eating oranges and lemons. This suggests that scurvy is a disease caused by

Only one answer is correct among these 4 choices:
- exposure to sea air
- a nutritional deficiency
- a microorganism
- lack of exercise

Could you tell me which one is correct?

a nutritional deficiency