Scientists performed a transformation experiment in which they added DNAse, protease, and RNAse to degrade DNA, proteins, and RNA respectively. They found no change in bacteria treated with protease and RNAse, but the transformation did not occur in those treated with DNAse. These results are most consistent with which of the following conclusions?

(A) The double helix is the structure of a DNA molecule.
(B) DNA is the hereditary material.
(C) DNA replication is semiconservative.
(D) DNA polymerase adds bases to only the 3' side of DNA.