Quite a controversial question. Though, my reasoning is more inclined towards answer choice C for the first problem. But, I still don't understand how come OA is D.
A -> not an issue
B -> type of air that would cause disturbance is not mentioned
D -> see B
E -> confuses info (see C)
C -> "To reduce refraction errors, the Chinese team carried in sea level to within five to twelve miles of Everest’s summit, decreasing the amount of air that light passed through on its way
...
A -> not an issue
B -> type of air that would cause disturbance is not mentioned
D -> see B
E -> confuses info (see C)
C -> "To reduce refraction errors, the Chinese team carried in sea level to within five to twelve miles of Everest’s summit, decreasing the amount of air that light passed through on its way
...
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