TOEFL Listening: ETS-TOEFL听力机经 - 43OFJ94D3BA8DJTRP$

Why does the professor mention Uranus' magnetic field? A. To point to the surprising similarity between Uranus and Earth B. To emphasize the limitations of remote observations in astronomy C. To point out a recent discovery about Uranus that contradicts earlier finding D. To explain one effect of Uranus' distance from the Sun