—What about the protection?

—Let’s keep the surface         dirt by putting a cover over it.

    A．far from B．free from    C．apart from   D．away from

—What about the protection?

—Let’s keep the surface       ____ dirt by putting a cover over it.

1. A.
   far from
2. B.
   free from
3. C.
   apart from
4. D.
   away from

 --What about the protection? 

--Let’s keep the surface _________ dirt by putting a cover over it.     

A. far from                 B. free from               C. apart from       D. away from

—What about the protection?
—Let’s keep the surface        dirt by putting a cover over it.