Correct Answer: low atmospheric pressure

Solution : The correct option is low atmospheric pressure .

The boiling point of water lowers with increasing altitude, owing to a decrease in atmospheric pressure. The atmospheric pressure is lower because there is less air above you at greater elevations. As a result, water molecules do not require as much thermal energy (heat) to overcome the lower atmospheric pressure and move from the liquid to the vapour phase (boiling) at lower temperatures than its original boiling temperature.