According to the passage, the sentence "But if the earth...for optimum comfort"(in the 3rd
According to the passage, the sentence "But if the earth...for optimum comfort"(in the 3rd paragraph) means ______.
A.there is an unseen hand controlling the earth's movement
B.there is an operating manual warning people against air-conditioning in the factory
C.people should prepare operating manuals to tell workers how to get greater comfort
D.people have been enjoying the most comfortable climate in Earth's history