Prior to the disaster, the climbers started to complain of fatigue, dizziness, lack of sleep, persistent headache, and impaired motor function. These are symptoms commonly associated with Acute Mountain Sickness (AMS). AMS is caused by not having enough oxygen. At high elevation, there is less oxygen available to the body because ______. Individuals who live at high altitudes (rather than just visiting them) _ suffer from AMS at the altitude in which they live.

a. the overall atmospheric pressure is lower so the partial pressure of oxygen is also lower, would not
b. oxygen make up a smaller percentage of the air, would
c. oxygen makes up a smaller percentage of the air, would not
d. the overall atmospheric pressure is lower so the partial pressure of oxypen is also lower, would

As an individual rises higher on a mountain, he will experience a situation where the air becomes increasingly thin. This means that the oxygen density becomes reduced each time the altitude becomes higher, this reduction in air causes a lower atmosphere pressure, since the pressure of the oxygen gas is also low, which makes breathing difficult and can cause Acute Mountain Sickness' symptoms. However, people who already live in high attitudes, have their bodies adapted to this situation, which means that they do not suffer from these symptoms.