To reduce noise pollution underwater and help protect marine animals like whales, the best option from the provided choices would be:
B - Use quieter methods to power boats, like sails.
This option directly addresses the source of noise pollution by suggesting a method that generates less noise. The other options either do not effectively reduce noise pollution (like increasing ship traffic or relocating animals) or could potentially still expose marine animals to harmful levels of noise (like requiring ships to travel in specific paths). Using quieter technologies would likely create a more conducive environment for marine life, particularly for species that rely on sound for communication.