Please answer the following question: John wanted to see how he would fare in high altitude compared to ground-level. So, he first measured his responses in ground-level. He labeled this part of the study as case A. Then he board on an airplane to reach high altitude, and measured his responses there. He labeled this part of the study as case B. Now, John knows how he needs to prepare for a high altitude hiking. Would case B see higher or lower air density than case A?
Answer:
lower