Which of the following statements does not accurately describe stem cells?

a. embryonic stem cells make up the inner cell mass of a blastocyst.
b. the use of stem cells is without any objections since it can be used in therapies to humans.
c. adult stem cells are multipotent and can differentiate into many types of cells.
d. the use of stem cells may allow scientists to use undifferentiated cells to repair or replace bad cells.