TOEFL Reading: ETS-TOEFL阅读机经 - 5NQ35PY5KBB895K6L$

According to paragraph 6, why is life unlikely to be found on any planet that lacks both an atmosphere and a surface or subsurface liquid medium A. Organic molecules must be protected from solar radiation by a surface layer of liquid. B. Planets that lack both of these features are probably too small to have been hit by many asteroids or comets carrying organic matter. C. Organic molecules need a liquid or gaseous environment to bring them together so they can interact. D. An atmosphere is needed to protect organic molecules from being destroyed by asteroids and comets.