The Federal Aviation Administration Limits the Number of Hours Flight $\backsim$

Multiple Choice

The Federal Aviation Administration limits the number of hours flight crews can be at high altitudes, $\backsim$ 10,000 m.One of the reasons is because

A) the crews can suffer from altitude sickness.
B) at high altitudes there are more gamma rays that can damage human tissues.
C) at high altitudes the air is thinner so there is less oxygen.
D) they do not want the crews to accrue too many frequent flyer miles.
E) None of the above statements is correct.