Recently, scientists have become increasingly concerned about pollution and its effects on weather. Actually, man's pollution of the atmosphere is not nearly as great as nature's. In fact, man is the lesser offender compared to nature itself. Specifically, active volcanoes, evaporation of impure water, and wind erosion of the landscape spew 8.5 billion tons of chemicals into space each year. Man's contribution consists of a mere half billion tons. What man contributes, though, is unable to escape very far into the atmosphere, so he must breathe; eat, and drink his own pollutants. Further research by environmental scientists is required to determine if gradual weather changes are related to atmospheric pollution.

Q. Underline the sentence which supports the correct answer for question No. 2.