"Adult" Stem Cells Are More Accurately Called Tissue-Specific or Somatic

"Adult" stem cells are more accurately called tissue-specific or somatic stem cells because

A) they are also present at prenatal stages of development.
B) some adults do not have them.
C) whether they are present or not in an adult depends upon the individual's level of maturity.
D) an adult body also contains embryonic stem cells.