A crew member falls overboard near your vessel's engine while it is running. What is a serious injury risk from the vessel's propeller that you should be aware of?

1. Propeller strike, which can cause severe injury or death — engines should be cut immediately when someone is in the water nearby
2. There is no risk since propellers automatically stop near people
3. The only risk is minor scratches to the propeller itself
4. Propellers cannot cause injury below the waterline