Concept: The boiling point refers to the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. The boiling point of water varies with the air pressure. The boiling point of a liquid at high pressure is higher than the boiling point of the same liquid at atmospheric pressure. Explanation: The normal boiling point of water is 100 degrees Celcius. The boiling point of the water is affected by its purity. So, the impurities in the water increase the boiling point because impurities decrease the water molecules during boiling. The temperature at which vapor pressure equals normal sea-level air pressure is known as the normal boiling point. The boiling point of water at sea level is 100oC. Water boils at 212oF at sea level. At low pressure and high altitude, the boiling point is low due to the decrease in atmospheric pressure. From 100oC it may decreases to 93oC to 96oC. Thus, the correct answer is only C.