The author's conclusion in the final sentence of the passage is based in part on which of the following points? A. Elsewhere on Mars there are likely to be patches of magnetized terrain similar to those that the Mars Global Surveyor detected. B. Planets other than Mars could have been affected by the chunks of debris that pelted the inner solar system 3.0 billion years ago. C. A global magnetic field on Mars could have remagnetized metallic particles that had lost their magnetic field. D. Not all collisions between debris chunks and planets result in the formation of craters. E. Impacts much smaller than the ones that probably created the craters in the Terra Sirenum region do not heat rocks to temperatures above 600 degrees Celsius.