Manatees are an endangered mammal species that live in bodies of water in Florida. Manatees migrate from summer habitats to winter habitats and look for safe areas to feed and raise their young. People in boats need to give space to manatees to protect them from harm. What might conservationists do to increase manatee populations?

A. Increase the number of boats
B. increase the local fish population
C. increase the oxygen available in the water
D. increase the amount of protected habitat available