In paragraph 2, the author implies which of the following about the collapse of the Mayan city-states? A. The fact that vegetation had grown over the ruins of Mayan buildings indicates that environmental degradation did not contribute to the Mayan collapse. B. Early explorers supposed that there was a catastrophic collapse of the Mayan city states largely because this view fit their preconceived ideas about lost civilizations. C. The condition of the tall pyramids and carved stones discovered by early explorers proves that Mayan city-states were violently overthrown. D. The Mayan cities were abandoned because they became submerged in vegetation.