Why Are Scientists So Optimistic About Using Stem Cells in Regenerative

Why are scientists so optimistic about using stem cells in regenerative medicine?

A) If we can use adult stem cells and reprogram them for therapeutic use,we would have an unlimited supply of cells to use.
B) Reprogramming adult cells means we can use patients' cells and circumvent many of the rejection problems that arise in transplantation.
C) Use of adult stem cells makes research and development much easier and less controversial.
D) All of the above.
E) None of the above.