IMPUGN:（）

单项选择题Which of the following best describes the organization of the third paragraph of the passage（）

A．A theory is proposed, considered, and then amended.
B．Opposing views are presented, elaborated, and then reconciled.
C．A problem is described, then a solution is discussed and its effectiveness is affirmed.
D．A view is advanced, then refuted, and an alternative is suggested.
E． A hypothesis is presented, qualified, and then reaffirmed.

单项选择题The passage suggests that which of the following would be true if volcanic eruptions did not take place（）

A．The environment would likely contain fewer non-biodegradable pollutants, due to lesser quantities of sulfurous gases and ash clouds.
B．Greenhouse gas effects on rising global temperatures would likely be somewhat less worrisome than those postulated by scientists today.
C．Acid rain produced by heavy industry would likely be more of a problem than it currently is, given the tendency of volcanic eruptions to hasten atmospheric cycles.
D．Global warming effects caused by human activities would be far more substantial than they are today if volcanic cooling effects ceased to take place.
E．The environment would likely be cooler, for the atmosphere would contain fewer sulfurous gases and ash clouds.