During the infancy days of cardiac transplantation, nonhuman primate hearts were transplanted into humans to save lives. This type of transplantation is best described by which one of the following?
Allograft: transplant from one species to the same species Autograft: transplant from one region of a person to another region Isograft: transplant from one person to a genetically identical person Xenograft: transplant from one species to another species