What is the concept of continental drift primarily about?

The concept of continental drift primarily concerns the idea that continents have not always been in their current positions but were once joined together in a single supercontinent known as Pangaea. This theory, which was notably proposed by Alfred Wegener in the early 20th century, suggests that continents drift over geological time due to tectonic forces. The notion of a supercontinent provides a framework to explain the similarities in geological structures, fossil distributions, and climatic patterns found across continents that are now widely separated.

The idea that continents were once part of a larger landmass helps to explain why certain fossils of plants and animals have been discovered on different continents, supporting the idea that they were once connected. This aspect is crucial in understanding the dynamic nature of Earth's geology and its history. The other options, while related to tectonics in different ways, do not capture the essence of continental drift as directly as the concept of a supercontinent does.