While visiting her grandma, Buttercup becomes somewhat restless. In an attempt to comfort Buttercup, her grandmother says, "Why don’t you play with the doll in my bedroom?" Buttercup goes to get the doll but returns crying and says, "That’s not doll. Doll has red hair and sleeps in my room." Buttercup’s behavior is best explained by

Underextension

Explanation:Underextension occurs when a child learns a new description of something but the child doesn't understand that this word extends to other things which falls within the same category. For example Buttercup probaly only learned the description of a doll from the doll that her parents bought her which is red hair and is always in her room now she has only restricted a description to this first doll that her parents probably bought , she no longer extends this meaning to all other dolls.

Underextension

Explanation:

Underextension

Underextension is when a child learns a word for something and just restricts it to one thing in that category, without extending it to other things in the same category. In this case Buttercup understands doll to mean her red hair doll that sleeps in her room and does not have the ability to process the thought( extend that thinking) that the doll in her grandma"s bedroom is equally a doll.