A typical 1 1/2-year-old child has a vocabulary of about 50 words. Which of the following is such a child least likely to do?

A) show some indication of understanding the meaning of words
B) link several words together to form a sentence
C) repeat a word that someone else has just said
D) say a word that no one else has said to the child in the last minute

Linking several words together to form a sentence is a developmental milestone that is typically achieved between the ages of 2 and 3 years old. At 1 1/2 years old, a child's language abilities are still developing and they are more likely to repeat or say single words rather than forming sentences. Therefore, choice B is the least likely action for a child with a vocabulary of 50 words.