Seagrass beds provide many benefits to the near-shore ecosystem, such as providing oxygen, stabilizing sediment, creating nursery grounds for many marine species, and acting as a food source for sea turtles and manatees. This unique habitat is diminishing in locations with increased coastline development and boating activity. Which type of regulation can best protect seagrass-bed habitat?

Control populations of manatees and sea turtles.
Fence in seagrass areas so they will not be overexploited.
Limit or ban motorized boats in critical seagrass communities.
Require developers to install seawalls when building near the coast.