Which of the Following Statements About Children's Use of Private

Which of the following statements about children's use of private speech is true?

A) Young children's use of private speech when in the presence of others is a possible sign of developmental delay.
B) Young children talk to themselves primarily as a form of entertainment.
C) Private speech typically ceases at about the same time children begin to string three words together.
D) Vygotsky believed private speech eventually becomes thought.