The author of the passage asserts which of the following about titanic collision models? A. Such models are conclusive with respect to certain anomalies within the solar system, but leave numerous other anomalies unexplained. B. Such models are more likely than are earlier models to account for the formation of multi-ring basins. C. Such models may be particularly useful in explaining what happens when the impacting bodies involved are of highly dissimilar mean densities. D. Such models have been tested to such a degree that they are quickly reaching the point where they can be considered definitive. E. Such models are so tempting that they run the risk of being used indiscriminately to explain unusual planetary features.