Cells of the inner cell mass in an early mammalian embryo can be isolated and grown in culture. Which of the following is NOT true regarding these cells?

A) They are totipotent.
B) They can be introduced into another developing embryo where their progeny become incorporated into the resulting adult animal, even into its germ line.
C) They are stem cells.
D) They can be manipulated in culture to give rise to almost any type of differentiated cell.