At high altitudes, the atmospheric pressure is lower compared to sea level. This means that the pressure exerted on the water molecules is also lower. Option 2 correctly states that the boiling point of water reduces due to lower atmospheric pressure.

When the atmospheric pressure is low, the boiling point of water decreases, and it can start boiling at a lower temperature than it would at sea level. This is because the vapor pressure of the liquid reaches the atmospheric pressure faster, causing the water to boil and evaporate.

Using a pressure cooker is preferable at high altitudes because it helps to maintain a higher pressure inside the cooker than the surrounding atmospheric pressure. This higher pressure increases the boiling point of water inside the cooker, allowing the food to cook properly.

Option 1, which states that the boiling point of water reduces due to higher atmospheric pressure, is incorrect. Higher atmospheric pressure would actually increase the boiling point of water, making it take longer for the water to reach its boiling point.

Options 3 and 4 are not relevant to the boiling point of water at high altitudes. Reduced gravitational force and increased ozone content do not directly affect the boiling point of water.