Water boils at a lower temperature when heated at the top of a mountain than at sea-level because at the top of the mountain the?

A. saturation vapour pressure of water is higher than at sea-level
B. sun adds more heat to the water
C. temperature is lower than at sea- level
D. relative humidity of the atmosphere is lower
E. pressure of the atmosphere is lower

Correct Answer:

Option E – pressure of the atmosphere is lower