[单项选择]　　Scientists studying the effect of large volcanic eruptions on global climate have long focused on the major quantities of carbon dioxide (C02), a gas known to contribute to the greenhouse effect, produced by these eruptions. It is well observed that such greenhouse gases trap heat radiated from the surface of the earth, thereby forming a type of insulation around the planet. The greenhouse effect is essential for ecological equipoise because it maintains the temperature of the planet within habitable parameters, but there is growing concern that man-made production of gases such as CO[,2] from the burning of fossil fuels may be threatening the system’’s tolerance, and have resulted in excessive warming on a global scale. While volcanic eruptions indubitably metabolize and accumulate C0[,2] in the atmosphere, it has been recently discovered that their impact is virtually trivial compared to the quantity produced by human activities, especially heavy industry. In reality, the more subs
A. The deep and enduring effect that volcanic eruptions have on the environment
B. The process by which classic volcanic eruptions tend to occur
C. The relative dearth of cases with scientists can judge the effects of volcain eruptions
D. A sample case with which later volcanic explosions are compared
E. The global cooling effects of one of the best-studied volcanic eruptions