Induced pluripotent stem (iPS) cells ______________________.
选项：

A:are created by the expression of a set of key genes in cells derived from adult tissues so that these cells can differentiate into a variety of cell types.
B:require a supply of donor egg cells, such as embryonic stem cells.
C:can differentiate into a greater variety of adult tissues than embryonic stem cells.
D:are created by nuclear transplantation.