What Is the Difference Between Underextension and Overextension

Multiple Choice

What is the difference between underextension and overextension?

A) Underextension is applying a word more narrowly than usual, and overextension is applying a word too broadly.
B) Overextension is applying a word more narrowly than usual, and underextension is applying a word too broadly.
C) Underextension occurs when infants begin speaking their first words, and overextension begins after they start using more than one-word sentences.
D) Overextension occurs when infants begin speaking their first words, and underextension begins after they start using more than one-word sentences.