Since the altitude OF sea level is 0, and the hiker in Death Valley is below sea level, the equation you would write would be : -10 + 10. This is because the joker went from BELOW sea level, to the altitude OF sea level. So, the answer should be A
The most logical situation would be A, the hiker starts at -10 feet the increases by 10 feet.
B. is close to A. but it wouldn't explain how the hiker stops at 0 feet. It'll just explain how he decreases by 10 feet going down to -20 feet
C. would be the same way w/ B. but now the elevation is above sea level and not below
D. however might confuse you into thinking that it is the correct answer because of the hiker starting at 0 feet. D. describes the hiker at 0 feet but then describes him increasing by 10 feet.
