What Does It Mean That There Are Optimal Periods for the Development

Multiple Choice

What does it mean that there are optimal periods for the development of language and even times during which learning is critical

A)  If language is not developed during that time frame, it cannot be developed later. 
B)  Language development is very important at that time. 
C)  Language development is necessary but can be established at a later date if necessary. 
D)  Trial-and-error cannot produce adequate results within this time frame.