Copernicus’s theory is now the basis ______ all our ideas of the universe are built.

Copernicus’s theory is now the basis ______ all our ideas of the universe are built.

1. A.
   to which
2. B.
   on which
3. C.
   for which
4. D.
   by which

Copernicus’s theory is now the basis ______ all our ideas of the universe are built.