Which of the following may be considered warning signs of a communication disorder for a mobile infant (6 to 18 months)?
a. misunderstanding questions most of the time
b. often misunderstood by others
c. limited or no interest in interacting in a familiar environment
d. using only short, simple sentences

I would suggest the answer is c

not a because young children generally still have a hard time fully comprehending questions or conversations. not b because it is very likely a child of such a young age won’t speak in a perfect manner and would be misunderstood. not d because kids that young generally cannot form complex sentences

C because kids that age usually are very interested in interaction specially in a familiar environment