Babbling with adult-like stress and intonation, at about ten months, is the:

1. The final stage of babbling is conversational babbling, also called the jargon stage. 2. It usually appears by about ten months of age. 3. It is defined as pre-linguistic vocalisations in which infants use adult-like stress and intonation. 4. Cooing comes earlier, at about two months, and uses mainly vowel-like sounds. 5. The holophrastic and telegraphic stages involve real words, so they cannot be pre-linguistic. 6. So the answer is the jargon stage. **Why the other options fail:** - Cooing comes around two months and is vowel-like, without adult stress and intonation. - The holophrastic stage uses single real words. - The telegraphic stage uses two-word sentences, so it comes later and is not pre-linguistic. _Source: Wikipedia, "Babbling", section "Timeline of typical vocal development" (revision 1379794682)_