The correct option is C Neither RNA nor protein could be the genetic material
Avery, MacLeod and McCarty observed that in the experimental tubes to which RNases and proteinases were added, the transformation could happen. This indicated that neither RNA nor protein could be the genetic material.
Among the three sets of experimental tubes that Avery, MacLeod and McCarty used, those to which RNAse and proteinase were added, still retained the ability to transform R-strain to live S-strain. It was only in the tubes to which DNase was added, that transformation could not happen. Therefore, neither RNA nor protein could be the transforming principle.