Final answer:
Portuguese scholarly accounts, astronomical charts, and accurate records of the direction and intensity of winds improved the safety of sailing on the ocean.
Step-by-step explanation:
All of the given options contributed to the improvement of safety in sailing on the ocean except for b. Newton's discovery of gravitation. Portuguese scholarly accounts, astronomical charts, and accurate records of the direction and intensity of winds all played a role in enhancing safety.
Learn more about improvement of safety in sailing on the ocean