Explanation:

- Water boils at its boiling point, which is identified at standard atmospheric pressure (1 atm) and sea level.

- The boiling point of water is commonly known to be 100°C at sea level and 1 atm pressure.

- This is due to the nature of water molecules and their hydrogen bonds, which require this specific temperature to shift from liquid to gas.

- Option 1: 50°C – This is incorrect since water is still in liquid form at this temperature.

- Option 2: 150°C – This is incorrect; water boils at a lower temperature.

- Option 3: 200°C – This is incorrect as well. Water does not need to reach this temperature to boil under standard conditions.

- Option 4: 100°C – This is the correct boiling point for water at standard atmospheric pressure and sea level.