Which type of stem cells are described as pluripotent?

Pluripotent stem cells are characterized by their ability to differentiate into nearly all cell types of the body, with the exception of extra-embryonic tissues such as the placenta. This distinctive feature means they can give rise to any cell type that comes from the three germ layers: ectoderm, mesoderm, and endoderm. An example of pluripotent stem cells is embryonic stem cells, which can develop into various specialized cells, such as neurons, muscle cells, and blood cells; however, they cannot form the placental tissues.

This differentiation capability highlights why the option indicating that pluripotent stem cells can become many cell types but not placental cells is accurate in describing pluripotency. The other types of stem cells mentioned do not align with the definition of pluripotent cells; for instance, those that can only become blood cells would be classified as multipotent, and those that can only form cardiac tissue would be classified as unipotent stem cells, which have an even narrower potential for differentiation.