Amelia is 3 years old and is beginning to develop more complex language skills. however, when she's out in public, she still has trouble with knowing when to say what, and what to say to whom. amelia appears to be having trouble with the

The correct answer is the pragmatics of language. 

The pragmatics of language refer to the knowledge of how to appropriately use language as a means of interaction in various social settings. Rather than being concerned with the accuracy and technicalities of language, the pragmatics of language focuses on the appropriate usage of language that is socially and culturally appropriate in different settings. For instance, while you might show less restraint and talk freely and casually with your friends at a bar, you will likely not talk in the same way to an interviewer when you are applying for a job.