I can't believe that an ________ boy can paint so well.

A. eleven years old

B. eleven-year-old

C. eleven year old

D. eleven-years-old

I can’t believe that an ________ boy can paint so well.

1. A.
   eleven years old
2. B.
   eleven-year-old
3. C.
   eleven year old
4. D.
   eleven-years-old