The "Rare Earth Hypothesis" Holds That Earth-Like Planets Will Prove

The "rare Earth hypothesis" holds that Earth-like planets will prove to be quite rare. Which of the following statements best sums up the current status of the debate over this hypothesis?

A) We do not have enough data to settle the debate, because counterarguments can be made for each argument suggesting Earth-like planets may be rare.
B) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are common.
C) The debate raged for a while, but is now settled. We are now quite certain that Earth-like planets are rare.
D) It is no longer discussed, because as part of its broad cover-up of UFOs, the United States government has classified all the material relating to this debate as Top Secret.