Which of the Following Best Summarizes the Conclusions of Researchers

Which of the following best summarizes the conclusions of researchers that have examined toddlers' acquisition of words?

A) They are quite slow to acquire new vocabulary, requiring many repetitions over several days before they acquire and retain new words.
B) They acquire expressive words through fast-mapping and referential words through overextension.
C) They often acquire new words after hearing them applied to their referents only once or twice.
D) They acquire referential words through fast-mapping and expressive words through overextension.