A measure of your cardiorespiratory endurance tells a fitness professional: Your aerobic fitness, or how efficiently your heart is working.
The answer is D because when you get a head injury your most likely to have a concussion from the impact which will cause you to loss consciousness and have blurred vision and dizziness.
I believe you are free to hike without training.
D. Hike
the surroundings or conditions in which a person, animal, or plant lives or operates.
sources:https://www.google.com/search?q=what+is+enviorment&oq=what+is+enviorment&aqs=chrome..69i57j0l5.4423j0j7&sourceid=chrome&ie=UTF-8
