GRE Reading Comprehension: JiJing 352-GRE阅读机经352篇 - JH6SO24LER7S140TJ

The author of the passage most likely mentions Mars' "oscillating tilt" primarily in order to A. provide evidence for a proposition about the potential effects of cometary impacts B. emphasize the absence from our solar system of normal planets C. contrast the rotational axis of Mars with that of Venus D. characterize the role of other planets in the solar system in earths development E. emphasize the importance of the Moon to the development of life on Earth