Final answer:
By 9 months, infants would have achieved cognitive and language milestones including babbling, using gestures, and responding to their name. Option 4 is correct.
Step-by-step explanation:
By 9 months of age, you would expect an infant to have reached several milestones in cognitive and language development. These include:
- Babbling and imitating sounds: By this age, infants start to make babbling sounds, repeating single syllables like "ma-ma" or "da-da".
- Using simple gestures: Infants at this stage can use simple gestures like waving or pointing to communicate their needs or interests.
- Responding to their own name: By 9 months, infants typically respond to their own name, showing an understanding of verbal cues.
Infants at 9 months of age would have achieved all of these cognitive and language milestones.