Answer the following question given this paragraph: 

A newborn baby has a soft spot on the top of its head. Over the next few months, the soft spot gradually hardens. What explains this?.


Q: A newborn baby has a soft spot on the top of its head. over the next few months, the soft spot gradually does what?

 Choices:

- weakens

- grows

- shrinks

- hardens

A:
hardens
