Say you have gone camping in the mountains. And that you meet a river on way up. From the river, you are going to take water because you know you will need it. So you took the water and continued the journey up. Now you have come to a high altitude. Now you are thirsty. We can't trust water so we boil it to kill germs and bacteria. You notice that the water has boiled quickly. Now the reason is that higher altitudes have low atmospheric pressure. So the boiling point decreases.
Now you might be wondering why I gave such a lengthy description. My aim is to tell the answer with some imagination so that it will get stuck in your head for a really long time so that you don't have to waste points and time.
