The correct answer is: C. Air pressure.
The temperature at which water boils depends on the surrounding pressure. At sea level, water boils at 100 degrees Celsius. However, at higher altitudes, the air pressure is lower, and water will boil at a lower temperature. For example, at an altitude of 10,000 feet, water boils at 80 degrees Celsius.
Air temperature, relative humidity, air density, and the specific heat of air do not have a significant effect on the boiling point of water.
Air temperature is the measure of how hot or cold the air is. It is measured in degrees Celsius or Fahrenheit. The air temperature does not have a significant effect on the boiling point of water. This is because the boiling point of water is determined by the pressure of the air, not the temperature.
Relative humidity is the amount of water vapor in the air compared to the maximum amount of water vapor that the air can hold at a given temperature. The relative humidity does not have a significant effect on the boiling point of water. This is because the boiling point of water is determined by the pressure of the air, not the amount of water vapor in the air.
Air density is the mass of air per unit volume. The air density does not have a significant effect on the boiling point of water. This is because the boiling point of water is determined by the pressure of the air, not the density of the air.
The specific heat of air is the amount of heat required to raise the temperature of one gram of air by one degree Celsius. The specific heat of air does not have a significant effect on the boiling point of water. This is because the boiling point of water is determined by the pressure of the air, not the specific heat of the air.