You are high up in the mountains and boil water to make some tea. However, when you drink your tea, it is not as hot as it should be. You try again and again, but the water is just not hot enough to make a hot cup of tea. Which is the best explanation for this result? 

(a) High in the mountains, it is probably very dry, and so the water is rapidly evaporating from your cup and cooling it. 

(b) High in the mountains, it is probably very windy, and so the water is rapidly evaporating from your cup and cooling it. 

(c) High in the mountains, the air pressure is significantly less than 1 atm, so the boiling point of water is much lower than at sea level. 

(d) High in the mountains, the air pressure is significantly less than 1 atm, so the boiling point of water is much higher than at sea level.