TOEFL Reading: ETS-TOEFL阅读机经 - S514L65433F3G4AGL$

According to paragraph 3, why did geologists initially hypothesize the existence of ancient land bridges across continents A. To explain how the continents may have drifted to their present-day positions B. To explain how organisms could spread across distant continents C. To argue against Wegener's theory of continental drift D. To help explain the present-day positions of the Southern Hemisphere continents