Answer:
RNA was the genetic material
Explanation:
If avary, Macleod, and McCarty would have seen that only RNAse treatment of the heat-killed bacteria prevented the transformation of genetic virulence than might have concluded that RNA is the genetic material as transformation does not occur because the RNAase degraded the RNA.
But if the genetic material is DNA then RNAase will not work because RNAase can not degrade DNA and then DNA will pass from virulent heat killed strain to nonvirulent strain and will cause transformation.