Read the following passage carefully.
In the early twentieth century, the scientific consensus regarding Earth’s geological history was firmly rooted in "fixism"—the paradigm asserting that the relative positions of the continents were immutable. When Alfred Wegener proposed his theory of continental drift in 1912, positing that continents had slowly plowed through the ocean floor, the geological establishment mobilized vigorously to defend the fixist model. The most formidable challenge for fixists was accounting for the striking paleontological continuity across widely separated landmasses. The fossilized remains of the Permian freshwater reptile *Mesosaurus* had been discovered in both Brazil and South Africa, while the heavy seeds of the *Glossopteris* fern were found distributed across South America, Africa, India, and Antarctica.
Because these organisms lacked the anatomical capacity to traverse thousands of miles of open ocean, fixist paleontologists proposed the existence of massive, ancient "land bridges"—transoceanic causeways that supposedly connected the continents during the Paleozoic and Mesozoic eras but had since subsided beneath the waves. This ad hoc hypothesis preserved the immutability of continental positions while explaining the biological distribution.
However, the land bridge hypothesis inadvertently collided with the emerging principle of isostasy, a fundamental geophysical concept demonstrating that the Earth's crust floats on a denser, plastic mantle. According to isostasy, the lighter granitic rock comprising continental crust cannot simply sink into the denser basaltic rock of the ocean floor, just as an iceberg cannot sink entirely into water. By asserting that continental-type rock had subsided to form the ocean floor, land bridge theorists implicitly contradicted the very laws of buoyancy governing the Earth's lithosphere. Furthermore, the volume of water displaced by these hypothetical sunken continents would have raised global sea levels dramatically, flooding the interiors of the remaining landmasses—a catastrophic inundation for which there was no geological evidence in the stratigraphic record.
Thus, while the land bridge hypothesis successfully neutralized the biological anomalies without abandoning fixism, it introduced geophysical paradoxes that were, ironically, far more mathematically intractable than Wegener's initial proposal of drifting continents.
Based on the passage, match each specific textual detail on the left with the logical inference that can most strongly be drawn from it on the right.
- The passage describes the seeds of the Glossopteris fern as "heavy."The plant's geographic spread across multiple continents could not have relied primarily on wind currents crossing open oceans.
- The passage compares continental crust floating on the mantle to an iceberg in water.Granitic rock masses cannot achieve negative buoyancy relative to the denser mantle material.
- Fixists proposed that ancient transoceanic causeways "subsided beneath the waves."Portions of present-day deep ocean basins were hypothesized by some scientists to have once been dry land.
- There is no stratigraphic evidence of catastrophic flooding of continental interiors.The total volume of Earth's ocean water was not drastically displaced by sinking continental structures.