The giant-impact hypothesis as described in the passage answers all of the following questions EXCEPT: A. What happened to the rock that surrounded the impactor's core after the impactor hit Earth? B. What happened to the impactor's core after the impactor hit Earth? C. Where did the impactor that collided with Earth originate? D. Why is the Moon's iron core small relative to that of Earth? E. What was the size of the impactor relative to that of Mars?