Final answer:
Future neuroblast cells at the beginning of neurulation in Xenopus give rise to neural crest cells, notochord cells, and epidermis cells.
Step-by-step explanation:
The correct answer is c. Neural crest cells. At the beginning of neurulation in Xenopus, future neuroblast cells give rise to neural crest cells, notochord cells, and epidermis cells. The notochord cells, derived from the mesoderm, send signals to the ectodermal cells to form epidermal cells as well as the neural plate.