Final answer:
The correct answer is A) East: Odd thousand feet, West: Even thousand feet, as it is a standard aviation practice used to prevent collisions.
Step-by-step explanation:
If you are traveling eastbound, the possible cruising altitude is at odd thousand feet, and if you are traveling westbound, it is at even thousand feet. The correct answer to the question is A) East: Odd thousand feet, West: Even thousand feet.
This rule is used to ensure the safety of air travel by minimizing the risk of collision between aircraft traveling in opposite directions. For example, a plane going eastward could cruise at 35,000 feet, while one going westward might fly at 36,000 feet.