Which of the following, if true, would cast most doubt on Phinney's estimate of the probability of Earth rocks hitting Mars? A. Rather than going in random directions, about 25 percent of all particles ejected from Earth go in the same direction into space. B. Approximately 100 meteorites large enough to make a noticeable crater hit the Earth each year. C. No rocks of Earth origin have been detected on Mars. D. The velocity of rocks escaping from Earth's gravity is lower than the velocity of meteorites hitting the Earth. E. No craters more than 60 miles across have been found on Mars.