It can be inferred from the passage that the "planetary scientists" would be most likely to agree with which of the following statements concerning the development of complex life forms on Earth? A. It might have occurred earlier in Earth's history if cometary impacts had been less frequent than they were. B. It could have occurred if Earth's orbit were 1 percent larger than it is but not if Earth's orbit were 5 percent smaller. C. It probably follows a pattern common on other terrestrial planets that occupy planetary systems containing gas giants. D. Its dependence on the effect that Jupiter's gravitational shield has on Earth was difficult to recognize prior to 1995. E. It has been contingent on conditions elsewhere in Earth's solar system as well as on conditions on Earth itself.