Final answer:
When fueling a boat, it's essential for safety to open all windows and hatches before the fueling process to provide proper ventilation and prevent the build-up of flammable vapours.
Step-by-step explanation:
When fueling a boat, it is advisable to open all windows and hatches before beginning the process of fueling. This is done to ensure proper ventilation and to prevent the accumulation of flammable vapours within the boat's interior spaces. The correct answer to the question "At what point should you open all windows and hatches when fueling?" is d) either before or after fueling. It's crucial for safety reasons to allow any fumes to dissipate and reduce the risk of fire or explosion.