Alexander Is Hiking Up Mt

Alexander is hiking up Mt. Everest, and recently reached the base camp at 12,000 feet. While there, he decides to make some tea, and puts a thermometer in the boiling water. To his surprise, the thermometer tells him the water is boiling at 96 °C. Why is this happening?

A) Water boils more quickly when you watch it.
B) The thermometer is broken.
C) The pressure is lower at higher elevations, and results in a lower boiling temperature.
D) The number of solutes in the air is higher at higher elevations, resulting in boiling point depression.
E) Alex is suffering from oxygen deprivation, and is reading the thermometer incorrectly.