Mars Rovers Have Uncovered Lava Rocks Containing Olivine and Pyroxene

Multiple Choice

Mars rovers have uncovered lava rocks containing olivine and pyroxene. What conclusion has been drawn from this?

A) These rocks dissolve quickly in water, thus Mars must have been dry for several billion years.
B) These rocks contain water, so the surface must have been submerged at some time during the last billon years.
C) These rocks contain microfossils that might be the remnants of living organisms. This greatly increases expectations of past life on Mars.
D) These rocks form at high temperature, suggesting that Mars formed closer to the Sun than it is now.