Multiple choice question

Following is the sequence of generating tidal energy:

1)      During high tide water flows into the inlet and gets trapped when the gate is closed.

2)      Floodgate dams are built across inlets.

3)      By this method oceanic tides can be used to generate electricity.

4)      After the tide falls outside the floodgate, the water retained by the floodgate back to the sea via a pipe that carries it through a power-generating turbine.