He is so skillful that he can draw a picture at an object in      a human hair.

1. A.
   one-twentieth the thicker than
2. B.
   one-twentieth the thick of
3. C.
   one-twentieth the thickness of
4. D.
   one-twenty thicker than

He is so skillful that he can draw a picture at an object in       a human hair.

       A．one-twentieth the thicker than B．one-twentieth the thick of

       C．one-twentieth the thickness of D．one-twenty thicker than