Question

for centuries, people have been puzzled over what caused dinosaurs to die off. today, there are several theories about what caused the extinction of dinosaur there are two primary theories, and scientists who study these theories fall into two main categories—intrinsic gradualists and extrinsic catastrophists.
the intrinsic gradualists believe that increased volcanic activity at the end of the cretaceous period led to the dinosaurs dying out. according to this theory, volcanoes all over the world were erupting at different intervals for a period of several million years. soot and ash from these eruptions may have gradually accumulated in the atmosphere and blocked the sunlight causing the earths surface to cool. this climate change may have led to the extinction of dinosaurs. the volcanoes may have affected the earths surface as well. there is a layer of rock in the earths crust known as the cretaceous - tertiary (k - t) boundary. the layer is found worldwide, and it contains a high level of iridium, a type of metal. the k - t boundary marks the end of the cretaceous period and the beginning of the tertiary period. some scientists believe the high level of iridium found in the k - t boundary may have come from molten rock that spewed from the volcanoes.
the extrinsic catastrophists believe that a giant comet or meteor crashed into earth. the crash may have been the catalyst for the extinction of dinosaurs. the impact of such an object would have thrown large amounts of debris into the air all at once. the debris would have blocked out the sunlight and caused the planet to cool. the impact would also have caused earthquakes, tsunamis, and other natural disasters. some scientists argue that the high level of iridium in the k - t boundary may have come from the meteor rather than from the volcanoes. some of these scientists believe that several comets or meteors collided with earth over a relatively short period of time. these theorists think the extinction of dinosaurs resulted from the multiple impacts.
although some evidence supports each theory, neither of the theories is conclusive. none of the theories explain why the dinosaurs went extinct while many
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how do the second and third paragraphs show that the extinction of dinosaur has divided the scientific community?
a. the author contrasts two groups of scientists with different views on how dinosaurs became extinct.
b. the author lists the pros and cons of the extrinsic catastrophists and intrinsic gradualists theories.
c. the author states the problem with earths climate and provides a solution to prevent future changes.
d. the author organizes the events that led to the extinction of dinosaurs in chronological order.

Explanation:

The second paragraph outlines the intrinsic gradualists' theory linking dinosaur extinction to long-term volcanic activity, while the third paragraph presents the extrinsic catastrophists' theory centered on a sudden meteor/comet impact. By presenting these two distinct, opposing scientific viewpoints, the text shows a division in the scientific community over the cause of dinosaur extinction. Option A correctly describes this contrast of two scientist groups with differing views. Option B is incorrect as no pros/cons are listed for either theory. Option C is irrelevant, as no climate solution is discussed. Option D is wrong, as the text does not organize events chronologically.

Answer:

A. The author contrasts two groups of scientists with different views on how dinosaurs became extinct.