How did the land masses of ancient continents appear in relation to each other?

The correct choice highlights the concept that the continental land masses of ancient continents had shapes that suggested they could fit together seamlessly, much like pieces of a jigsaw puzzle. This idea is supported by the theory of continental drift, proposed by Alfred Wegener, which posits that the continents were once part of a supercontinent known as Pangaea. Over millions of years, Pangaea broke apart, and the continents drifted to their current positions.

The jigsaw puzzle analogy is particularly significant because many geographic features, such as mountain ranges, coastlines, and rock types, align across continents when they are positioned as they were in the past. This finding provides strong evidence for the existence of ancient connections between the land masses. Consequently, the notion of continents fitting together supports the idea of plate tectonics, where the movement of tectonic plates shapes the Earth's surface over geological time.

The other options do not accurately describe the configuration of ancient land masses. Random scattering fails to account for the geological evidence linking different continents. A straight line along the equator does not reflect the complex arrangement and orientations of the continents, and vast deserts separating them overlooks the geological links that have been observed in the rock and fossil records across continents.