The correct options are
B High tides help fishermen.
D High tides help in navigation.
High tides act as natural clensers by washing off the debris dumped on the shores and the ports. They help in collecting salt as they bring brackish water. High tides help in navigation by raising the water level close to the shore. This helps ships to navigate shallow harbours easily. High tides also bring fish closer to the shore, giving fishermen plenty more catch. Finally, high tides help in harnessing tidal energy through the generation of electricity.