Scientists have recently developed a process by which a skin cell from a human can be triggered to develop into a human heart muscle cell. This is possible because _________.

A. Most cells in the human body contain the genetic instructions for making all types of human cells;

B. A skin cell is produced when all genes in the cell are expressed; turning off some genes in the cell results in a heart cell;

C. Scientists can add new genes to old cells to make them take different forms;

D. A skin cell expresses only recessive alleles, so it can be triggered to produce dominant heart cell alleles;

E. It is easy to mutate the genes in skin cells to produce the alleles required for other cell types