19. In 1997, Dolly the sheep was cloned. Which of the following processes was used?
(A) use of mitochondrial DNA from adult female cells of another ewe.
(B) fusion of an adult cell's nucleus with an enucleated sheep egg, followed by incubation in a surrogate.
(C) separation of an early stage sheep blastula into separate cells, one of which was incubated in a surrogate ewe.
(D) isolation of stem cells from a lamb embryo and production of a zygote equivalent.
(E) replication and dedifferentiation of adult stem cells from sheep bone marrow.