Generalizing from Research Presented in the Text, If a 4-Year-Old

Generalizing from research presented in the text, if a 4-year-old was observed speaking to a 2-year-old, what kind of speech would the 4-year-old be most likely to use:

A) the same kind of speech he uses when talking to his mother
B) the same kind of speech he uses when talking to his older brother
C) the same kind of speech he uses when talking to his preschool teacher
D) a simpler version of his normal speech