Which stage of development is characterized by babbling?

The stage of development characterized by babbling is indeed the young infant stage. Babbling typically occurs during the period when infants are developing their vocal cords and experimenting with sounds that lead to speech. This stage usually spans from around 4 to 6 months of age, where infants begin to produce repetitive consonant-vowel combinations, such as "ba-ba" or "da-da."

Babbling is a crucial part of language development, as it signifies that the child is beginning to learn how to communicate and express themselves before forming actual words. During this stage, infants are also more engaged with their environment and their caregivers, often responding to sounds and attempting to mimic those sounds, thus laying the foundation for future language acquisition.

In contrast, mobile infants begin to master movement, young toddlers start to use simple words and phrases, and older toddlers begin forming more complex sentences and refining their speech further. Therefore, this aligns with the significant milestones in vocal development occurring during the young infant stage, making it the correct choice.