Which skill indicates appropriate language development in a 9-month-old infant?

At 9 months of age, infants typically engage in babbling, which is an important milestone in language development. Babbling involves repeating consonant-vowel combinations, such as "ba," "da," or "ma," and serves as a precursor to more complex speech. This stage allows infants to practice the sounds they will use as they start to form words later on.

The ability to babble strings of sounds at this age indicates that the infant is beginning to experiment with their vocalization and is developing the foundational skills necessary for speech. Babbling also helps with the social aspects of communication, as it encourages interaction between the infant and caregivers.

Other milestones, such as saying simple words like "dada," typically emerge a bit later in development. While pointing to objects might indicate some understanding and engagement with their environment, it is not as strong an indicator of language skills specifically. Similarly, the ability to repeat phrases is more expected in older infants and toddlers who are further along in their language development. Thus, babbling is the most relevant indicator of language development for a 9-month-old.