Final answer:
Avery, MacLeod, and McCarty would have concluded that protein is the genetic material if only the samples treated with protease did not transform bacteria. Their experiments, however, established that DNA was the transforming principle, identifying DNA as the genetic material.
Step-by-step explanation:
If Avery, MacLeod, and McCarty had found that samples of heat-killed bacteria treated with RNase and DNase transformed bacteria, but that samples treated with protease did not, they would have concluded that protein is the genetic material. This conclusion would be drawn because protease, which degrades proteins, prevented the transformation, indicating that proteins must be involved in the genetic information's transmission. Their actual experiment, however, showed that only the samples treated with DNase, which degrades DNA, did not transform the bacteria, leading them to conclude that DNA was the transforming principle.
Their systematic elimination study involved using specific enzymes to degrade proteins, RNA, and DNA, and observing the ability to transform the R strain of bacteria. Their findings that DNA degradation prevented transformation were crucial in identifying DNA as the genetic material, despite initial skepticism from the scientific community.