Final answer:
People did not initially believe in Wegener's continental drift theory because there was no known mechanism for how continents could move, the fossil record was not effectively explained, and the idea was too unconventional at the time. The correct answer to the student's question is (D) All of the above.
Step-by-step explanation:
When Alfred Wegener first proposed the theory of continental drift, he encountered scepticism for several reasons. These reasons combine to provide the correct answer to the question, which is (D) All of the above.
(A) There was no known mechanism for how the continents could move: Scientists of the time could not imagine how large landmasses could shift positions on the Earth's surface because the mechanism, which we now know as plate tectonics, had not yet been understood or discovered.
(B) The fossil record showed that similar plants and animals lived on different continents, which was indeed a part of Wegener's evidence in favour of continental drift. However, without a mechanism to explain how continents moved, many scientists doubted the validity of using such evidence to support his radical hypothesis.
(C) The idea that the continents could move was simply too radical for many people to accept at the time. The concept of continents moving across the Earth's surface was too revolutionary and did not fit within the existing scientific understanding of the time.
It wasn't until the development of the theory of plate tectonics several decades later that the scientific community began to accept the idea of moving continents, recognizing the extensive evidence supporting it and understanding the mechanism behind it.