Which Example Demonstrates Underextension

Multiple Choice

Which example demonstrates underextension?

A) Abigail refers to any animal with four legs as a "dog."
B) Billy knows the word "ball," but he only calls a football a ball.
C) Maddie knows that cows, sheep, horses, and chickens all live on a farm, but she calls them all "horses."
D) Tyler uses the word "butter" to refer to anything that he puts on bread, including peanut butter, cream cheese, and jelly.