Final answer:
Andrija Mohorovičić discovered the transition between the crust and mantle, known as the Mohorovičić discontinuity or Moho, not Alfred Wegener who proposed the theory of continental drift.
Step-by-step explanation:
The transition between the crust and the mantle was discovered by Andrija Mohorovičić, a Croatian seismologist. This boundary is known as the Mohorovičić discontinuity, often shortened to the Moho. In contrast to Mohorovičić, Alfred Wegener made significant contributions to the field of geology with his theory of continental drift, proposing that the continents had once been part of a large supercontinent named Pangaea. Although widely recognized for this theory, it was not Wegener who discovered the crust-mantle transition. The correct answer to the question, "Who discovered the transition between the crust and mantle?" is B) Mohorovičić.