Which of the Following Statements About Babbling Is CORRECT

Which of the following statements about babbling is CORRECT?

A) In the development of babies' babbling, it can be said that they are "learning the words before the tune."
B) When babies babble with a falling intonation at the end of a string of sounds, it seems to signal a desire for a response.
C) When babies first start babbling, they typically babble all kinds of sounds, including some that are not part of the language they are hearing.
D) At about 9 or 10 months of age, the sound repertoire in babbling gradually shifts to include the set of sounds they do not hear spoken.
E) Babbling involves complex combinations of vowels that occur before cooing.