Final answer:
The evidence of similarly aged and composed mountain ranges across different continents supports the theory that these lands were once part of a single landmass, supporting the concept of continental drift and the former existence of supercontinents like Pangaea.
Step-by-step explanation:
The similarities in age and composition of rock formations in mountain ranges across continents, such as those between the Appalachian Mountains in North America and mountain ranges in Britain and Norway, as well as between mountain ranges in South Africa and Argentina, provide evidence in support of the theory that the continents that are currently separated were once joined together. This concept is best explained by plate tectonics and the existence of supercontinents, like Pangaea, which fragmented into the continents we know today.
The matching geological attributes across continents indicate that they were once part of the same landmass and have since drifted apart due to tectonic plate movements. This explains why mountain ranges that are separated by oceans today have similar geological histories and structures. The correct answer to the student's question is b) Continents that are now separated were once joined together.