The correct answer is 4 only.

• Tides are caused by the earth, moon, and sun's gravitational pull and their position.
• Tidal flows are of great importance in navigation and help the navigators and fishermen plan their activities. Hence, Statement 1 is correct.
• Harbors near rivers and within estuaries having shallow ‘bars’ at the entrance prevent ships and boats from entering into the harbor.
• Tides are also helpful in desilting the sediments and in removing polluted water from river estuaries. Hence, Statement 2 is correct.
• Tides are used to generate electrical power as their mechanical energy is used to drive a turbine that produces electricity. Hence, Statement 3 is correct.
• Tides vary in frequency, direction, and movement from place to place and also from time to time.
• Tides may be grouped into various types based on their frequency of occurrence in one day or based on their height.
• Tides based on the Sun, Moon, and the Earth Positions.
• The height of rising water varies depending upon the position of the sun and moon concerning the earth.
• The ‘tide generating force is the difference between the gravitational attraction of the moon and the centrifugal force. 
• The shape of bays and estuaries along a coastline can also magnify the intensity of tides.
• Funnel-shaped bays greatly change tidal magnitudes.
• It is not as such use in the Development of Coral Reefs. Hence, Statement 4 is incorrect.